Write the symbol for every chemical element that has atomic number greater than 70 and atomic mass less than 181.2 u.
Answer:
Lu
Hf
Ta
Explanation:
Lu- Lutecium
Atomic Number- 71
Atomic Mass-174.967
Hf- Hafnium
Atomic Number-72
Atomic Mass178.492
Ta- Tantalum
Atomic Number-73
Atomic Mass-180.948
The chemical elements that meet the criteria are Hafnium (Hf) and Tantalum (Ta).
The atomic number represents the number of protons in the nucleus of an atom, while the atomic mass represents the total mass of protons and neutrons in the nucleus of an atom.
Elements with atomic numbers greater than 70 are located in the bottom rows of the periodic table, known as the "lanthanides" and "actinides."
So, Atomic Number > 70 and Atomic Mass < 181.2 u
1. Hafnium (Hf) - Atomic Number: 72, Atomic Mass: 178.49 u
2. Tantalum (Ta) - Atomic Number: 73, Atomic Mass: 180.95 u
3. Tungsten (W) - Atomic Number: 74, Atomic Mass: 183.84 u
4. Rhenium (Re) - Atomic Number: 75, Atomic Mass: 186.21 u
Therefore, the chemical elements are Hafnium (Hf) and Tantalum (Ta).
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Which hypothesis of Thomson's atomic model was later found to be not true by Niels Bohr and why?
In 1904, J.J. Thomson published the Thomson model of the atom. The plum pudding model is often referred to as Thomson's model.
In 1897, he also made the electron discovery. Scientists Rutherford and Bohr subsequently refuted this theory. According to J.J. Thomson, an atom is a positively charged sphere with embedded negatively charged electrons.
Neils Bohr disproved it by demonstrating that any atom's mass is centred in its positively charged centre, while negatively charged electrons orbit the positive centre. In highly quantized energy levels, according to Bohr's theory, electrons orbit an atom's nucleus rather than being incorporated into it.
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Periodic Table Project: Element Presentation Instructions Click the links to open the resources below. These resources will help you complete the assignment. Once you have created your file(s) and are ready to upload your assignment, click the Add Files button below and select each file from your desktop or network folder. Upload each file separately.
do ions add another atom
yes ions add another atom
ions are electrically charged particles that can be created by either taking electrons away from neutral atoms to form positive ions or adding electrons to neutral atoms to produce negative ions. The quantity of protons remains constant during the formation of an ion.
Ionic bonds are defined as connections between atoms in which electrons are primarily transported from one atom to another. Since there is always some electron sharing between atoms, we say largely because the sharing in ionic bonds is relatively uneven. The bond has a stronger ionic character the more unequally the electrons are shared.
Between a metal and a non-metal, ionic bonding form. Ionic bonds, as opposed to covalent ones, involve the transfer of valence electrons between atoms.
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yes Ions can be combined with other atoms to create new elements or compounds.
Since they contain an equivalent number of protons and electrons, atoms are neutral particles. Ions are electrically charged entities that can be created by either taking electrons away from neutral atoms to form positive ions or adding electrons to neutral atom to form negative ions.An atoms become the ions when the neutral atom gain the electrons to formed anions and loses its electrons to formed cations.The anions can be combined with the cations through the ionic bond or electrostatic bond.The stable atoms is electrical neutral atom or an atom is not stable when it contains any charge over it like negative or positive charge.However not all ions are atoms, an atom can be an ion.
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What is a feature of object-oriented computing?
sstateless encapsulation of states platform-independentside-effect free
The feature of object-oriented computing is an encapsulation of states. The correct option is b.
What is object-oriented computing?Object-oriented computing, the short form, is OOP. A computer programming paradigm known as object-oriented programming (OOP) arranges the architecture of software around data or objects rather than functions and logic.
An object is a data field with particular characteristics and behavior. It contains data and codes. It is stored in the form of a procedure. Furthermore, it is a programming paradigm.
Thus, the correct option is b. encapsulation of states.
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Why is acid added to water first
Answer: because acid and water react in a vigorous exothermic reaction, releasing heat, sometimes boiling the liquid.
Suppose you need to prepare 128.2 ml of a 0.364 m aqueous solution of nacl. what mass, in grams, of nacl do you need to use to make the solution?
To prepare 128.2ml of a 0.364 M aqueous solution of NaCl.the mass in grams, of NaCl need to use to make the solution is 2.723 gm.
Molarity is defined as the no. of moles of solute per liter of solution.
Here,
Molarity = moles of solute / Liter of solution
0.36 M solution will contains 0.364 moles of NaCl.
therefore, volume of solution in L = ( 128.2 / 1000 ) L × 1 L
= 0.1282 L
that means, it will contain, no. of moles of NaCl
= (0.1282 L of solution × 0.364 ) / 1 L of solution
= 0.0466 moles of NaCl
now, molar mass of NaCl = 58.44 g/mol
so, 1 mol of NaCl has a mass of 58.44 g/mol
therefore, 0.0466 moles of NaCl will have mass of
= ( 0.0466 moles of NaCl × 58.44 g ) / 1 mole of NaCl
= 2.723 g
Thus,To prepare 128.2ml of a 0.364 M aqueous solution of NaCl .the mass in grams, of NaCl need to use to make the solution is 2.723 gm.
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If a capacitor is overcharged, the electrons from the negative plate could be pulled through the insulation to the positive plate. the capacitor is said to be ? .
If a capacitor is overcharged, the electrons from the terrible plate may be pulled through the insulation to the high-quality plate. the capacitor is stated to be shorted.
Overcharging could only mean exceeding its voltage rating.The capacitor can break down (internally short between terminals) overheat and or open circuit. Some capacitors can literally ooze chemicals or “pop” or explode and/or catch fire.while you join a capacitor to DC voltage, the capacitor will price to this voltage, and the charging current will drop to zero.
You need to make certain the voltage isn't better than the capacitor’s Shorting.
On AC, the capacitor will comply with the voltage, w/a put off. again, you need to make sure the voltage rating of the capacitor fits the voltage(In this situation peak voltage).
If the voltage is higher in either case-the capacitor may short.
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How many positional isomers of nonene are there? (consider only linear compounds, not branched isomers.)
2 linear positional isomers of nonene are there
Nonene have molecular formula is C₉H₁₈ called nonene no of possible isomers are 35 but including branched there are 35 isomers of nonene while linear compound mean only straight chain compound here straight chain compound are only 2 common name for nonene is non-1 ene there are so many isomers are seen in nonene Straight chain, Octanes, Heptanes,3,1 Dimethylheptanes,3,2 Ethylheptanes, Hexane, 4.1 Trimethyl. 4.2 Methyl+Ethyl, Pentane. in nonene class of organic compounds known as unsaturated aliphatic hydrocarbons. these are aliphatic hydrocarbons that contains one or more unsaturated carbon atoms. These compounds contain one or more double or triple bonds.
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Give examples of:
3 Solid to solid mixtures
3 Solid to liquid
3 liquid to liquid
3 liquid to gas
thanks
Answer:
Explanation: Solid to Solid mixtures
1. Iron+Sulphur
2. Pottasium Nitrate+Potassium Chlorate
3. Ammonium Chloride+Sodium Chloride
Solid to Liquid Mixtures
1. Salt+Water
2. Sand+Water
3. Calcium Carbonate+Water
Liquid to Liquid Mixtures
1. Alcohol+Water
2. Oil+Water
3. Kerosene+Water
Liquid to Gas Mixtures
1. Hydrogen+Oxygen
2. Hydrogen Chloride+Nitogen
3.Air (Air is a mixture of many gases)
Compound X2Y is 60% X by mass. Calculate the percent of Y by mass of the compound X2Y2.
The molar mass of compound tells you the mass of 1 mole of that substance. The percent by mass of y in x₂y₂ is 57.14%
What is molar mass ?
Molar mass of a substance is the mass in grams of one mole of the compound. In a substance, the amount of entities present e.g. atoms, molecules, ions, is defined as a mole. A mole of any substance is 6.022×1023 molecules
In compound x₂y, the percentage mass of x is 60%. The percentage mass of y is 40 %. Let the compound weighs M , 2 units of x weigh 0.6M, 1 unit of x weighs 0.3* M and one unit of y weight 0.4*M.
In the compound x2y2, the percentage mass of y is
0.4*2 ÷ (0.4*2 + 0.3* 2 ) = 8 ÷ (.8+.6) = 0.8 ÷ 1.4 = 57.14 %
The percent by mass of y in x₂y₂ is 57.14%.
Thus, the percentage by mass of y in x₂y₂ is 57.14.
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Adding earthworms to a compost pile typically increases the rate at which the organic
matter in the pile decomposes. A learner wonders whether adding other organisms to the
compost pile will have a similar effect on the rate of decomposition. She decides to an-
swer this question by performing an experiment.
Formulate a valid hypothesis that the learner could test in her experiment.
Based on this hypothesis, identify the independent variable and dependent variables for the
learner's experiment.
..
.
Compost
In the experiment performed on the compost:
A valid hypothesis for this experiment is: Adding living organisms to compost increases its rate of decomposition.The independent variable are the types of living organisms added to the compostThe dependent variable is the rate of decomposition of compostWhat is are variables in an experiment?Variables in an experiment are factors that are under the control of the researcher and which brings about changes in the result of the experiment.
There are three types of variables in an experiment, they are;
Independent variableDependent variableConstant variableThe independent variable is the variable which affects the result of the experiment by controlling the dependent variable.
The dependent variable changes as a result of changes in the independent variable.
The constant variable is kept constant or unchanged by the researcher.
Considering the experiment performed on the compost:
A valid hypothesis for this experiment is: Adding living organisms to compost increases its rate of decomposition.The independent variable are the types of living organisms added to the compostThe dependent variable is the rate of decomposition of compostLearn more about dependent and independent variables at: https://brainly.com/question/25223322
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How many protons, electrons and neutrons are in an isotope of the element with an atomic number of 79 and a mass number of 200
The number of protons, electrons and neutrons are in an isotope of the element with an atomic number of 79 and a mass number of 200 is 79, 79 and 121 respectively.
What is atomic number?Atomic number of an element is the number of protons in an atom of the element while the atomic mass is the sum of the protons and neutrons in the atom.
The electron number is equal to the number of protons in a neutral atom.
According to this question, the isotope of an element has an atomic number of 79 and a mass number of 200.
Number of protons = 79Number of electrons = 79Number of neutrons = (200 - 79) = 121Therefore, the number of protons, electrons and neutrons are in an isotope of the element with an atomic number of 79 and a mass number of 200 is 79, 79 and 121 respectively.
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What mass of liquid mercury would fill a glass tube with a diameter of 16.0 mm to a height of 25.0 cm? the density of mercury is 13.53gcm3.
The mass of liquid mercury that can fill glass tube is 680.365 gm.
We know that ,
Volume of cylinder = π[tex]r^{2} h[/tex]
where r is the radius of cylinder and h is the height
Here diameter of glass tube is 16mm
Thus the radius r = 8 mm
= 0.8 cm
Volume of glass tube = π [tex]0.8^{2}[/tex][tex]*25[/tex] [tex]cm^{3}[/tex]
Density of mercury given is [tex]13.53gm/cm^{3}[/tex]
We know that
Density = Mass / Volume
∴ [tex]13.53gm/cm^{3}[/tex] = Mass/ π[tex]0.8*0.8 * 25[/tex]
Mass = 13.53 *π0.8*0.8*25
= 680.36 gm
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I NEED HELP ASAP ANYONE PLEASE
When an arrow (--->) is used in a chemical equation, on which side of the arrow are the reactants found?
Select one:
a. Above the arrow.
b. Below the arrow.
c. To the left of the arrow.
d. To the right of the arrow.
Answer:
C. to the left of the arrow
Explanation:
The reactants (the chemicals that initiate the chemical reaction) are represented on the left, while the products (the substances that result from the reaction) are represented on the right. An arrow sign ("→" commonly read aloud as "yields") separates the two.
Sorry if I'm wrong
Answer: C
Explanation:
C
what are the frequency of a photon with a wavelength of 360 nm. report your answers to three significant digits.
The frequency of a photon with a wavelength of 360 nm frequency of a photon is 8.33 × 10¹⁴ s⁻¹.
Given,
The wavelength of photon = 360 nm or 3.60 × 10⁻⁷
three × 10⁸ m/s is the speed of mild.
We need to discover the frequency of a given photon.
The frequency of a photon is described as the wide variety of waves that pass via a set point in a unit of time.
therefore, f = c/λ
where f is the frequency, c is the velocity of light, and λ is the wavelength of the photon.
f = 3 × 10⁸/ 3.60 × 10⁻⁷
Or, f = 0.8333 × 10¹⁵ s⁻¹
Or, f = 8.33 × 10¹⁴ s⁻¹
Hence, the frequency of the photon is 8.33 × 10¹⁴ s⁻¹.
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Why does the first ionization energy generally increase across a period for the main group elements?
Ionization energy : the minimum amount of energy demands to detach an electron from an isolated atom.
Ionization energy also known as potential energy.
The charge of the nucleus increases from side to side in a row and so there is an increase in the attraction in the middle of the nucleus and the surrounding electrons. As we move from side to side in a periodic table from left to right, the nuclear charge increases. This is because of increasing nuclear charge, which concludes in the topmost electron being more strongly leap to the nucleus.
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what name is given to this molecule? a positively charged molecule. this molecule consists of three hydrogen atoms bonded to an oxygen atom. what name is given to this molecule? a positively charged molecule. this molecule consists of three hydrogen atoms bonded to an oxygen atom. methane hydronium ion water glucose hydroxide ion
Answer:
h20
Explanation:
science, 3 hydrogen and one oxygen make h2o
[tex]H_3O^+[/tex], hydronium ion is the name given to this molecule. Therefore, the correct option is option B among all the given options.
The smallest recognisable unit which which a pure material may be split while retaining its composition and chemical characteristics is a molecule, which is a collection of two or more atoms. Until portions consisting of tiny molecules are reached, the division of a sample for a substance onto progressively smaller parts does not result in a change with respect to its composition as well as its chemical characteristics. [tex]H_3O^+[/tex], hydronium ion is the name given to this molecule.
Therefore, the correct option is option B among all the given options.
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Which would be considered a chemical change? burning charcoal no answer text provided. adding water to vinegar freezing water
One type of chemical reaction is combustion. Carbon dioxide is produced when carbon combines with oxygen in the combustion of charcoal, for example. Carbon and oxygen are reactants, or the chemicals that initiate a chemical reaction. The process produces carbon dioxide. However, this change is just physical.
As the constituent molecules' composition remains unchanged: 11.19% hydrogen and 88.81% oxygen by mass. Physical change can be classed as either reversible or irreversible. When we burn coal, a chemical reaction occurs, and new substances such as carbon dioxide and water are formed. Burning coal is considered as a chemical change since it results in the production of new compounds.
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How many moles of naoh are present in 25.0 ml of a 0.1000 m naoh solution?
a. 100 mol
b. 2.50 x 10-3 mol
c. 0.100 mol
d. 2.50 mol
e. 25.0 mol
2.50 x 10⁻³ mol naoh are present in 25.0 ml of a 0.1000 m naoh solution
Here Molarity formula is used to find moles in solution
Molarity = no of moles of solute/volume of solution
M= molarity, V = volume , n= no of moles
M=0.1000m , V=25.0ml , n=?
M=n/v(ml)×1000
n=MV/10³ = 0.1000×25.0/10³ = 2.50 x 10⁻³ mol
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9.The density of mercury is 13.6 g/mL.
What is the mass in kilograms of a 2 L
commercial flask of mercury?
Answer:
27.2 kg
Explanation:
13.6 * 2 L of commercial flask of mercury = 27.2 kg.
Hope this helps! Have a good day! :D
Suppose you heat a 4. 31 g sample of a n a 2 c o 3 hydrate. After thorough heating, the mass of the compound is 3. 22 g. Based on the data, what is the formula for the hydrate you started with?.
Suppose we heat a 4. 31 g sample of a Na2Co3 hydrate. after thorough heating, the mass of the compound is 3. 22 g based on the data, Na₂CO₃ • 2H₂O for the hydrate we start with this formula.
Here compound are Na₂Co₃ then mass of compound is 3.22g and molar mass is 105.98g/mol
Moles of compound (anhydrate Na₂CO₃) = mass / molar mass = 3.22 g / 105.98 g mol = 0.0304 mol mass
So here compound Na₂Co₃ are given and we start with formula Na₂CO₃ • 2H₂O for the hydrate.
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True or false: Chemical properties can be observed only when the substances in a sample of matter are changing into different substances.
What is the most-correct statement about the polypeptide with the primary sequence atavistic?
The most appropriate answer among the option is a polypeptide with a primary sequence it contains four nonpolar neutral residues.
What is polypeptide?
A longer, unbroken, continuous peptide chain is known as a polypeptide. Peptides therefore belong to the wide chemical families of biological polymers and oligomers, along with nucleic acids, oligosaccharides, polysaccharides, and others.
A polypeptide with typically more than 50 amino acids is referred to as a protein. One or more polypeptides with a physiologically functional structure make up a protein. Proteins commonly interact with other proteins, other macromolecules like DNA or RNA, or intricate macromolecular complexes.
Amino acids that have been incorporated into peptides are called residues. A water molecule is released as a result of every amide connection.
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The complete hydrolysis of a protein produces a mixture of? polypeptides free amino acids polypeptides and free amino acids dipeptides and free amino acids
The complete hydrolysis of a protein produces a mixture of free amino acids.
Acids are molecules or ions that can donate protons, known as Bronsted-Lowry acids, or form covalent bonds with electron pairs, known as Lewis acids. The first category of acids is proton donors or Brønsted-Lowry acids.
No oil is either an acid or a base. Neutral. Oil is a neutral, nonpolar chemical. That is, it is a viscous liquid at room temperature. It is immiscible with water, but soluble in alcohol and ether. Whole eggs are relatively pH neutral, but egg whites are one of the few foods that are naturally alkaline, with an initial pH of as high as 7.6 when eggs are laid, but the alkalinity increases as eggs age and reach increases. the pH of 9.2.
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How can we see all four colors from a hydrogen gas dischrarge tube simutaneously?
There are thousands of hydrogen atoms so together they can let off or group up to form all four colors.
Hydrogen is a chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. Under standard conditions, hydrogen is a diatomic molecular gas of the formula H2. It is colorless, odorless, tasteless, non-toxic, and highly flammable.
Hydrogen is an energy carrier that can be used to store, transfer, and deliver energy generated from other energy sources. Hydrogen fuel can be produced today by several processes. The most commonly used methods today are natural gas reforming (a thermal process) and electrolysis. It is found in the Sun and most stars, and the planet Jupiter is composed primarily of hydrogen. On Earth, hydrogen is most abundant as water. As a gas in the atmosphere, it is present in trace amounts, less than 1 ppm by volume.
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The general molecular formula for alkanes is cnh2n 2. what is the general molecular formula for cycloalkanes with two rings?
The general molecular formula for alkanes is cnh2n 2. The general molecular formula for cycloalkanes with two rings CnH2n−2.
Cycloalkanes are hydrocarbons with a ring type structure. The reason of ring formation is because they are saturated compounds. The general formula of the cycloalkanes is CnH2n where n is the number of carbon atoms.
cyclopentane, Cyclobutane, cyclohexane, and cycloheptane, cyclooctane are some example of cycloalkanes and Cyclopropane is considered one of the smallest cycloalkanes.
Cycloalkanes have a lot of uses. They are used in the medical industry for the production of drugs. These compounds are also used in hair and food industries.
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Determine the excess reactant and calculate the mass of the remaining excess reactant after 20.0 grams of al and 10.0 grams of o2 react.
The reactant in excess is Al (s)
The mass of remaining surplus reactant is 8.76 g
According to question
4 moles of aluminium reacts with 3 moles of oxygen, to make 2 moles of alumina.
Molar mass Al: 26.98 g/m
Molar mass O2: 32.00 g/m
Mass / Molar mass: Moles
20 g Al / 26.98 g/m = 0.741 moles 10 g O2/32.00 g/m 0.312 moles =
Let's find out the limiting reactant and reactant in surplus by rules of three: the 4 moles of Al reacts with 3 moles of O2
0.741 moles of Al reacts with (0.741.3)/4 = 0.555 moles
Now we know that are needed 0.555 moles of O2 to consume all the Al but we only have 0.312 moles of O2.
The O2 is the limiting reactant, so the Al is the reactant in excess.
Let's make another rule of three
3 moles of O2 reacts with 4 moles of Al
0.312 of O2 reacts with (0.312 .4)/3 = 0.416
We need 0.416 moles to consume all the O2 and we have 0.741 moles of Al.
When we use 0.416 moles from 0.741 it remains 0.325
0.325 moles . 26.98 g/m = 8.76 grams
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For the following 3 experimental set-ups identify:
1. the independent variable
2. the dependent variable
3. controlled variables
4. and then write a valid hypothesis for the experiment.
The independent variable is the type of liquid and the dependent variable growth of the plants.
What is an experiment?An experiment is used to establish the relationship between causes and effect in each of the following cases, let us determine the dependent and independent variable.
1) The independent variable is the type of liquid and the dependent variable growth of the plants. The constants are the plants and the land. A valid hypothesis is; "The growth of the plants depends on the type of liquid used to water the plants"
2) The independent variable is the mode of transport and the dependent variable is the time taken to reach the market. The constant is the distance covered. A valid hypothesis is; "The time taken to arrive at the grocery store depends on the mode of transport used"
3) The independent variable is the kind of app and the dependent variable is the battery life. The constant is the phone used while the hypothesis is; "Certain apps delete the battery faster than others"
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21. When a sulfur atom reacts with other atoms, electrons in the atom's third energy level are involved. How many such electrons does a sulfur atom have?
The electrons in the atom's third energy level that are involved in chemical reaction are six in number.
How many electrons does sulfur have?
Sulfur is an element that can be found in group sixteen of the periodic table. It has a valency of two because it has six electrons in the outermost shell and shares two more electrons with another element in order to form a covalent bond.
There are three electron shells that could be found in sulfur. The first shell has two electrons, the second shell has eight electrons while the last shell has six electrons.
As such, the electrons in the atom's third energy level that are involved in chemical reaction are six in number.
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