Question

Question 21

What is the fundamental difference between covalent and ionic bonding?

In a covalent bond, the partners share a pair of electrons; in an ionic bond, one partner accepts electrons from the other.

Covalent bonds form between atoms of the same element; ionic bonds form between atoms of different elements.

Covalent bonding involves only the outermost electron shell; ionic bonding also involves the next electron shell inside the outermost shell.

In covalent bonding, both partners end up with filled outer electron shells; in ionic bonding, one partner does and the other does not.

Question 22

Which of the following statements regarding the oxygen atom of a water molecule is true?

Oxygen attracts electrons less strongly than the hydrogen atoms.

Oxygen is more positively charged than the hydrogen atoms.

Oxygen is attracted to the negatively charged atoms of other molecules.

Oxygen is more electronegative than the hydrogen atoms.

Question 23

In a water molecule, hydrogen and oxygen are held together by a ________ bond.

nonpolar covalent

hydrogen

polar covalent

double covalent

Question 24

The hydrogen atoms of a water molecule are bonded to the oxygen atom by ________ bonds, whereas neighboring water molecules are held together by ________ bonds.

polar covalent; ionic

ionic; covalent

polar covalent; hydrogen

hydrogen; polar covalent

Question 25

Which of the following statements regarding chemical reactions is false?

Some chemical reactions create electrons; others destroy them.

The reactants contain the same number of atoms as the products.

Chemical reactions involve the making and breaking of chemical bonds.

Although the atoms of a reaction's reactants and products are identical to each other, their molecular formulas differ.

Question 26

The tendency of water molecules to stick together is referred to as

adhesion.

cohesion.

polarity.

transpiration.

Question 27

As ice melts

water molecules become less tightly packed.

the water becomes less dense.

heat is released.

hydrogen bonds are broken.

Question 28

A solution with a pH of 7 is

weakly acidic.

weakly basic.

strongly acidic.

neutral.

Question 29

Compared to a solution of pH 3, a solution of pH 1 is

10 times more basic.

10 times more acidic.

100 times more acidic.

100 times more basic.

Question 30

Which of the following statements about pH is true?

An increase in hydrogen ion concentration means a decrease in pH scale units.

A single unit change on the pH scale is equivalent to a 1% change in hydrogen ion concentration.

Basic pH levels are less than 7.

The pH scale is a measure of oxygen ion concentration.

Answer 1

Ans21:

? In a covalent bond, the partners share a pair of electrons; in an ionic bond, one partner accepts electrons from the other.

--- covalent bond forms between any two atoms which have similar electronegativity and ionic bond forms between atoms with opposite electronegativity. Covalent bond involves sharing of electron, whereas ionic involves transfer of electrons.

Ans 22-

? Oxygen is more electronegative than the hydrogen atoms.

Ans23:

In water, oxygen and hydrogen are bound covalently.

? polar covalent bond.

Ans24:

The hydrogen atoms of a water molecule are bonded to the oxygen atom by ____polar covalent____ bonds, whereas neighboring water molecules are held together by ___hydrogen_____ bonds.

? polar covalent; hydrogen.

Ans 25:

? Some chemical reactions create electrons; others destroy them.

Ans26:

Water molecule stick each other by cohesion and stick to other surfaces by adhesion.

? cohesion

Ans27:

As ice melts

? hydrogen bonds are broken.

Ans 28:

pH 7 is

? neutral

Ans29:

A solution of pH 1 is 100timea more acidic than pH 3 solution.

?100 times more acidic.

Ans 30:

? An increase in hydrogen ion concentration means a decrease in pH scale units.

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