The number of electrons in the valence shell of an element of atomic number 14 is?
- A. 1
- B. 2
- C. 3
- D. 4
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 shape of ammonia molecule is?
- A. trigonal planar
- B. octahedral
- C. square planar
- D. tetrahedral
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
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
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
8g CH4 occupies 11.2 dm3 at s.t.p. What volume would 22 g of CH3CH2CH3 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
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
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
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