Question

1. an temperature rises, solids generally become more soluble in water, but gases become less soluble. if a saft drink contains high concentrations of sugar and carbon dioxide, which of the following may be expected to happen if it is cooled down?

a. sugar may precipitate out.
b. gas bubbles may form and produce foam
c. water may evaporate rapidly
a. a only
b. b only
c. a and b only
d. a and c only

page 3 of 6

1. an atom with just one electron in its outer shell will seek to shed that electron so that its outer shell is complete. an atom whose outer shell is missing just one electron will seek to complete that shell by acquiring an electron from another atom.

an ion is an atom that has become either negatively or positively charged. how can an atom become a negative ion?
a. by acquiring an electron from another atom
b. by bonding with a positively charged atom
c. by sharing an electrons with another atom
d. by transferring an electron to another atom

1. how does a catalyst speed up the reaction?

a. it increases the activation energy, making it harder for the reactants to turn into products.
b. it decreases the activation energy, making it easier for the reactants to turn into products.
c. it increases the activation energy, making it easier for the products to turn back into reactants.
d. it makes the reaction go backward.

1. which of the following statement is true for taste in food?

a. food containing bases taste sweet
b. food containing bases taste sour
c. food containing acid taste bitter
d. food containing bases taste bitter

1. molecules are constantly moving. in which state of matter do molecules move the fastest?

a. molecules move at the same rate in all three states of matter
b. gases
c. solids
d. liquids

1. what is the outcome of a displacement reaction between zinc metal and copper sulfate solution?

a. zinc sulfate and copper metal
b. copper and zinc oxide
c. zinc oxide and copper sulfate
d. copper sulfate and zinc chloride

Explanation:

Question 11

Step1: Analyze sugar solubility with cooling

Solids (sugar) solubility in water generally decreases with cooling (opposite of heating effect). So high - concentration sugar solution on cooling may have sugar precipitate (a is possible).

Step2: Analyze gas solubility with cooling

Gases (CO₂) solubility in water generally increases with cooling (opposite of heating effect). So on cooling, gas solubility increases, so gas bubbles (b) will not form (since more gas dissolves). Water evaporation (c) is faster at higher temperatures, so cooling slows evaporation. So only a is correct.

An atom has a neutral charge (equal protons and electrons). To become a negative ion, it needs more electrons (since electrons are negative). Acquiring an electron from another atom increases electron count, making it negative. Bonding with a positive atom doesn't directly make it negative. Sharing electrons (covalent bonding) doesn't create ions. Transferring an electron would make it positive (losing electron). So acquiring an electron (option A) makes it a negative ion.

A catalyst's role is to lower the activation energy of a reaction. Activation energy is the energy barrier reactants need to cross to form products. Lowering this barrier makes it easier for reactants to become products, thus speeding up the reaction. Option A says it increases activation energy (wrong), C says it increases for reverse (wrong), D says it reverses reaction (catalysts don't change reaction direction, just speed). So B is correct.

Answer:

A. a only

Question 12