Question

1a.

Potassium has an atomic number of 19 and a mass number of 39. What would result if an uncharged potassium atom lost one electron?

Select one:

a. The atomic number of the atom would remain 19, the mass number would be reduced to 38, and the atom would be an anion.

b. The atomic number would be reduced to 18, the mass number would remain 39, and the atom would be an anion with a +1 charge.

c. The atomic number would remain 19, the mass number would remain 39, and the atom would be a cation with a +1 charge.

d. The atomic number would remain 19, the mass number would remain 39, and the atom would have no charge.

1b.

Which organelle often takes up much of the volume of a plant cell?

Select one:

a. lysosome

b. central vacuole

c. Golgi apparatus

d. chloroplast

1c.

In the formation of table salt (NaCl), sodium is said to be:

Select one:

a. Oxidized

b. Reduced

c. Neutral

d. Energized

Answer 1

Ans-1a) Atomic number = number of protons.

Mass number = number of protons and neutrons taken together.

When an atom loses electron, it becomes a positive ion(cation) and the atomic number and mass number remains the same because these numbers do not depend on the number of electrons. Hence, potassium atom with atomic number 19 and mass number 39, will change to cation when it loses one electron. Therefore, the correct answer is- (c) the atomic number would remain 19, the mass number would remain 39, and the atom would be cation with a 1+ charge.

Ans-1b) Which organelle often takes up much ofthe volume of a plant cell- (b) central vacuole.

Plant cells often have a large central vacuole which takes up most of the volume of the cell.

Ans-1c) In the formation of table salt(NaCl), sodium is said to be- (a) oxidized.

Oxidation reactionis definedasa chemical reaction in which a chemical substance loses electrons while changing from reactant to product. In the formation of sodium chloride, sodium(Na) loses one electron which is gained by chlorine. Hence, sodium is said to be oxidized, whereas chlorine is said to be reduced.