1. Elements combine to form millions ofA. metals.
B. mixtures
C. compounds.
2. The forces that hold atoms together in combinations are called
A. energy bonds.
B. nuclear bonds.
C. chemical bonds.
3. Every electron has a
A. neutral charge.
B. positive charge.
C. negative charge.
4. The exact positions of the electrons in an atom cannot be determined because
electrons are always
A. moving
B. sharing.
C. changing
5. Compared with electrons that are closer to the nucleus, those that are farther
away have
A. less energy
B. more energy
C. equal energy


Answer 1

question no 1 answer is compounds

Answer 2

Final answer:

Elements combine to form millions of compounds. The force holding atoms together in these combinations are chemical bonds. Each electron has a negative charge, electrons are always moving, and have more energy the farther they are from the nucleus.


The elements can combine in many ways to create compounds, which amount to millions. When atoms connect or adhere to each other to shape those compounds, it happens through chemical bonds. In an atom, each electron has a negative charge, a characteristic that's vital for the creation of chemical bonds. Electrons are in constant movement, which means we cannot exactly determine their positions. As for the energy level of these electrons, those farther away from the nucleus have, in general, more energy than the ones located closer to the nucleus.

Learn more about Atomic Structure and Chemical Bonds here:



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Which of the following acids (listed with pKa values) and their conjugate base would form a buffer with a pH of 8.10?(A) HC7H5O2, pKa = 4.19(B) HF, pKa = 3.46(C) HClO, pKa = 7.54(D) HCN, pKa = 9.31(E) HClO2, pKa = 1.96
Rank the following elements from smallest tolargest atomic radius: Fr, F, Ge, Ru?

Vinegar, the commercial name for acetic acid, HC2Hs02, is a monoprotic organic acid. A 5% (w/v) solution of vinegar is used to titrate a sample of an antacid that contains CaCO3 is the only basic component. If one antacid tablet contains 800 mg of CaCOs in it, then calculate how many milliliters of vinegar should be required to completely neutralize the CaCO3 present in one tablet of antacid?


19.2 g of vinegar solution


Here we have the chemical reaction between acetic acid (CH₃COOH) and calcium carbonate (CaCO₃):

2 CH₃COOH +  CaCO₃ → (CH₃COO)₂Ca + CO₂ + H₂O

number of moles = mass / molecular weight

number of moles of CaCO₃ = 0.8 / 100 = 0.008 moles

Knowing the chemical reaction, we devise the following reasoning:

if       2 moles of CH₃COOH react with 1 moles of CaCO₃

then X moles of CH₃COOH react with 0.008 moles of CaCO₃

X = (2 × 0.008) / 1 = 0.016 moles of CH₃COOH

mass = number of moles × molecular weight

mass of acetic acid (CH₃COOH) = 0.016 × 60 = 0.96 g

Now to find the volume of vinegar acid (solution of acetic acid) with a concentration of 5% (weight/volume) we use the following reasoning:

if there are         5 g of acetic acid in 100 mL of vinegar solution

then there are   0.96 g of acetic acid in Y mL of vinegar solution

Y = (0.96 × 100) / 5 = 19.2 g of vinegar solution

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weight/volume concentration



1. On the basis of your results, what is the relationship between the temperature of the solvent and the rate of solution formation?


Answer: As the temperature increases, the rate of formation of solution increases.


Solvent is defined as a substance which is present in larger proportion in a solution. Solute is dissolved in the solvent to form a solution.

As, the temperature of the solvent increases, the kinetic energy of the particles of solvent increases and the intermolecular spacing between the solvent particles increases and therefore, this results in the more dissolution of the solute particles in the solvent and hence, the formation of solution increases.

Therefore, there is a direct relationship between the temperature of the solvent and the formation of the solution.


Hot temp = solution forming faster.


Salt in hot water dissolves faster than salt in ice water.

A sample containing only carbon, hydrogen, and silicon is subjected to elemental analysis. After complete combustion, a 0.7020 g sample of the compound yields 1.4 g of CO2, 0.86 g of H2O, and 0.478 g of SiO2. What is the empirical formula of the compound?


Answer: The empirical formula of compound is C_4H_(12)Si.


Mass of Sample= 0.702 g

Mass of CO_2 = 1.4 g

Mass of H_2O = 0.86 g

Mass of SiO_2 = 0.478 g  

First we have to calculate moles ofCO_2, H_2O and SiO_2 formed.

1. Moles of CO_2=(1.4g)/(44g/mol)=0.032mol

Now , Moles of carbon == Moles of CO_2 = 0.032

2.  Moles of H_2O=(0.86g)/(18g/mol)=0.048mol​​​

Now , Moles of hydrogen = 2* Moles of H_2O =2* 0.048=0.096mol

3.  Moles of SiO_2=(0.478g)/(60g/mol)=0.008 mol

Now , Moles of silicon = Moles of SiO_2 = 0.008 moles

Therefore, the ratio of number of moles of C : H : Si is  = 0.032 : 0.096 : 0.008

For the mole ratio, divide each value of moles by the smallest number of moles calculated.

For C= (0.032)/(0.008)=4

For H =(0.096)/(0.008)=12

For Si=(0.008)/(0.008)=1

Thus, C: H: Si = 4 : 12 : 1

The simplest ratio represent empirical formula.

Hence, the empirical formula of compound is C_4H_(12)Si.

A chemist designs a galvanic cell that uses these two half-reactions:O2 (g) + 4H+(aq) + 4e− → 2H2O (l) Eo =+1.23V
Zn+2 (aq) + 2e− → Zn(s) Eo=−0.763V

Answer the following questions about this cell.

Write a balanced equation for the half-reaction that happens at the cathode.
Write a balanced equation for the half-reaction that happens at the anode.
Write a balanced equation for the overall reaction that powers the cell. Be sure the reaction is spontaneous as written. Do you have enough information to calculate the cell voltage under standard conditions


Answer: The reaction is spontaneous and there is not enough information to calculate the cell voltage.


The substance having highest positive E^o reduction potential will always get reduced and will undergo reduction reaction.

Oxidation reaction occurs at anode and reduction reaction occurs at cathode.

  • For a:

The half reactions for the cell occurring at cathode follows:

O_2(g)+4H^+(aq)+4e^-\rightarrow H_2O(l);E^o_(cathode)=+1.23V

  • For b:

The half reactions for the cell occurring at anode follows:

Zn(s)\rightarrow Zn^(2+)+2e^-;E^o_(anode)=-0.763V    ( × 2)

  • For c:

The balanced equation for the overall reaction of the cell follows:

O_2(g)+4H^+(aq)+2Zn(s)\rightarrow H_2O(l)+2Zn^(2+)(aq)

For the reaction to be spontaneous, the Gibbs free energy of the reaction must come out to be negative.

Relationship between standard Gibbs free energy and standard electrode potential follows:

\Delta G^o=-nFE^o_(cell)

For a reaction to be spontaneous, the standard electrode potential must be positive.

To calculate the E^o_(cell) of the reaction, we use the equation:


Putting values in above equation, we get:


As, the standard electrode potential of the cell is coming out to be positive, the reaction is spontaneous in nature.

  • To calculate the EMF of the cell, we use the Nernst equation, which is:

E_(cell)=E^o_(cell)-(0.059)/(n)\log ([Zn^(2+)]^2)/([H^(+)]^4* p_(O_2))

As, the concentrations and partial pressures are not given. So, there is not enough information to calculate the cell voltage.

Hence, the reaction is spontaneous and there is not enough information to calculate the cell voltage.

Which is an example of the electromagnetic force? A compass needle points north toward Earth’s magnetic pole. An iron nail rolls off a table and falls to the ground. The moon pulls on the water in Earth’s oceans, causing tides. Protons that make up a nitrogen atom stay together in the nucleus.


a compass needle points north toward earths magnetic pole is an example of the electromagnetic force.

what is electromagnetic force ?

An electromagnetic force is one of the four fundamental forces a combination of both electrical and magnetic forces and this force is act up on the charged particles .

It  is inversely proportional to the inverse square of the distance between particles, electromagnetic force can be attractive or repulsive shows infinite range and this force holds atoms together in molecules.

This force can be produced by electromagnetic fields, electrostatic field, and magnetostatic field which affects all of the universal objects due to its infinite range.

This force causes electric and magnetic effects like repulsion between like electrical charges or the interaction of bar magnets, it is weaker than the strong force.

For more details regarding electromagnetic force, visit




a compass needle points north toward earths magnetic pole.


because of the earths magnetic field.

15.2 grams of CO2 = ? molecules of CO2



2.11 molecules of CO₂


Given data:

Mass of CO₂ = 15.2 g

Molecules of CO₂ = ?


Number of moles of CO₂:

Number of moles = mass/molar mass

Number of moles = 15.2 g/ 44 g/mol

Number of moles = 0.35 mol

Avogadro number.

It is the number of atoms , ions and molecules in one gram atom of element, one gram molecules of compound and one gram ions of a substance.  The number 6.022 × 10²³ is called Avogadro number.

1 mole = 6.022 × 10²³ molecules

0.35 mol × 6.022 × 10²³ molecules / 1 mol

2.11 molecules of CO₂