Which of the following is an example of a mixture?
Blood
Common salt
Sand
Washing soda
Calculate the percentage by mass of nitrogen in calcium trioxonitrate (V), Ca(NO3)2. [Ca = 40, N = 14, O = 16]
13.1%
27.6%
8.5%
17.1%
The droplets of water observed around a bottle of milk taken out of the refrigerator is due to the fact that
temperature of the milk drops as it loses heat
water vapour around the bottle gains energy from the bottle
water vapour in the air around the bottle loses energy to the bottle
the saturated vapour pressure of the milk equals the atmospheric pressure
The volume of a gas is V cm3 at P mmHg. What is its new volume if the pressure is reduced to half at constant temperature?
V cm3
V/2 cm3
2V cm3
4V cm3
Across a period from left to right, the general rise in first ionization energy is mainly due to
decrease in screening effect
increase in screening effect
decrease in nuclear charge
increase in nuclear charge
