A mixture of sand, ammonium chloride and sodium chloride is best separated by?

A. sublimation followed by addition of water and filteration

B. sublimation followed by addition of water and evaporation

C. addition of water followed by filtration and sublimation

D. addition of water followed by crystallization and sublimation

A pure solid usually melts?

A. over a wide range of temperature

B. over a narrow range of temperature

C. at a lower temperature than the impure one

D. at the same temperature as the impure one

At the same temperature and pressure, 50 cm³ of nitrogen gas contains the same number of molecules as?

A. 25 cm³ of methane

B. 40 cm³ of hydrogen

C. 50 cm³ of ammonia

D. 100 cm³ of chlorine

8g CH₄ occupies 11.2 dm³ at s.t.p. What volume would 22 g of CH₃CH₃ occupy under the same condition?

(C = 12, H = 1)

A. 3.7 dm³

B. 11.2 dm³

C. 22.4 dm³

D. 33.6 dm³

To what temperature must a gas 273 K be heated in order to double both its volume and pressure?

A. 298 K

B. 546 K

C. 819 K

D. 1092 K

For a gas, the relative molecular mass is equal to 2Y. What is Y?

A. The mas of the gas

B. The vapour density of the gas

C. The volume of the gas

D. The temperature of the gas

The densities of two gases, X and Y, are 0.5 g dm^-3 and 2.0 dm^-3 respectively.
What is the rate of diffusion of X relative to Y?

A. 0.1

B. 0.5

C. 2.0

D. 4.0

The shape of ammonia molecule is?

A. trigonal planar

B. octahedral

C. square planar

D. tetrahedral

An increase in temperature causes an increase in the pressure of a gas because?

A. it decreases the number of collision between the molecules

B. the molecules of the gas bombard the walls of the container more frequently

C. it increases the number of collision between the molecules

D. it causes the molecules to combine

The number of electrons in the valence shell of an element of atomic number 14 is?

A. 1

B. 2

C. 3

D. 4

Which of the following physical properties decreases down a group in the periodic table?

A. Atomic radius

B. Ionic radius

C. Electropositivity

D. Electronegativity