CHEMISTRY F4

A scientist wants to destroy microorganisms that spoils strawberries by using radioisotope. Which of the following isotopes is the most suitable?

• Krypton-85

• Cobalt-60

• Nitrogen-15

• Iodine-131

A gas tank contains 1 mole of propane gas, C3H8. How many hydrogen atoms are there in the gas tank?

(Avogadro constant = 6.02 × 10^23 mol-¹)

• 1 × 6.02 × 10^23

• 3 × 6.02 × 10^23

• 8 × 6.02 × 10^23

• 11 × 6.02 × 10^23

The average mass of a calcium atom is 40 times greater than 1/12 of the mass of carbon-12 atom. What is the relative atomic mass of calcium

• 3.3

• 12.0

• 40.0

• 80.0

Which of the following is TRUE when travelling across Period 3 from sodium to chlorine?

• The size of atom increases

• The relative atomic mass increases

• The number of proton in the atom decreases

• The electronegativity decreases

Element X reacts with nitrogen to form a compound with formula X3N2. What is the correct electron arrangement of X?

• 2.8.1

• 2.8.2

• 2.8.3

• 2.8.5

Calculate the mass of potassium hydroxide that is required to prepare 250cm³ of 2.0 mol dm-³ solution.

(RAM : H = 1, O = 16, K = 39)

• 22.4 g

• 28 g

• 56 g

• 112 g

Which of the following gas will decolourise the purple colour of acidified potassium permanganate (VII) solution?

• Nitrogen dioxide

• Sulphur dioxide

• Chlorine

• Ammonia

100cm³ of 1.0 mol dm-³ sulphuric acid reacts with excess sodium carbonate. What is the volume of CO2 gas release at standard temperature and pressure?

Molar volume of gas at standard temperature and pressure : 22.4 dm³ mol-¹

• 1.12 dm³

• 2.24 dm³

• 4.48 dm³

• 22.4 dm³

14.9 g of KCl is dissolved in distilled water to produce 0.4 mol dm-³ KCl solution. What is the volume of distilled water needed to dissolved KCl? (Molar mass : KCl = 74.5 g mol-¹

• 50 cm³

• 200 cm³

• 500 cm³

• 2000 cm³

Which substance is an alkali?

• Zinc oxide

• Magnesium oxide

• Potassium hydroxide

• Aluminium hydroxide