Chromatography is used to separate components of mixtures which differ in their rates of?
Which of the following is a example of a chemical change?
A. Dissoultion of salt in water
B. Rusting of iron
C. Melting of ice
D. Separating a mixture by distillation
The number of hydrogen ions in 4.9 g of tetraoxosulphate (IV) acid is?
(S = 32, O =16, H = 1, Na = 6.02 x 1023
A. 3.01 x 1022
B. 6.02 x 1022
C. 3.01 x 1023
D. 6.01 x 1023
What volume of oxygen will remain after reacting 8cm3 of hydrogen with 20cm3 of oxygen?
A. 10 cm3
B. 12 cm3
C. 14 cm3
D. 16 cm3
A gas sample with an initial volume of 3.25 dm3 is heated and allowed to expand to 9.75 dm3 at constant pressure. What is the ratio of the final absolute temperature to the initial absolute temperature?
Two cylinders A and B each contains 30 cm3 of oxygen and nitrogen respectively at the same temperature and pressure. If there are 5.0 moles of nitrogen, then the mass of oxygen is?
A. 3.2 g
B. 6.4 g
C. 80.0 g
D. 160.0 g
A liquid begins to boil when?
A. its vapour pressure is equal to the vapour pressure of its solid at the given temperature
B. molecules start escaping from its surface
C. its vapour pressure equals the atmosphere pressure