Cr2O72-(aq) + 14H+(aq) + 6l–(aq) → 2Cr3+(aq) + 3l
The change in the oxidation number of oxygen in the equation above is?
- A. 0
- B. 1
- C. 2
- D. 7
Which of the following is a redox reaction?
- A. KCI(aq) + H2SO4(aq) → KHSO4(aq) + HCI(aq)
- B. 2FeBr2(aq) + Br4(aq) → 2FeBr3(aq)
- C. 3AgNO(aq) + FeCl3(aq) → 3AgCl(aq) + Fe(NO3)3(aq)
- D. H2CO3(aq) → H2O(I)2- + CO2(g)
2CL–(aq) → CI2(g) + 2e-(aq). The above half-cell reaction occuring at the anode during the electrolysis of dilute ZnCI2 solution is?
- A. ionization
- B. oxidation
- C. reduction
- D. recombination
How many moles of copper would be deposited by passing 3F of electricity through a solution of copper (II) tetraoxosulpohate (IV)?
(F = 96 500 C mol–)
- A. 0.5
- B. 1.0
- C. 1.5
- D. 3.0
In the process of silver-plating a metal M, the metal M is the?
- A. anode and a direct current is used
- B. cathode and an alternating current is used
- C. anode and an alternating current is used
- D. cathode and a direct current is used
Neutralization involves a reaction between H3O+ and?
- A. CI-
- B. OH-
- C. NO3-
- D. CO32-
In general, an increase in temperature increases the solubility of a solute in water because?
- A. more solute molecules collide with each other
- B. most solutes dissolve with the evoltion of heat
- C. more solute molecules dissociate at hihger temperatures
- D. most solutes dissolve with absorption of heat
The difference between colloides and and suspensions is brought out clearly by the fact that while colloids?
- A. do not scatter light, suspensions do
- B. can be separated by filtration, suspension cannot be so separated
- C. can be separated by a membrane, suspensions cannot
- D. do not settle out on standing, suspensions do
When plastics and packaging materials made from chloroethene are burnt in the open, the mixture of gases released into the atmosphere is most likely to contain?
- A. ethane
- B. chlorine
- C. hydrogen chloride
- D. ethene
Deliquescent substances are also?
- A. efflorescent
- B. anhydrous
- C. hygroscopic
- D. insoluble
Helium is often used in observation balloons because it is?
- A. light and combustible
- B. light and non-combustible
- C. heavy and combustible
- D. heavy and non-combustible
Which of the following statements is FALSE about isotopes of the same element?
- A. They have the same number of electrons in their outermost shells
- B. They have different atomic masses
- C. They have the same atomic number and the number of electrons
- D. They have the same atomic number but different umber of elelctrons
The ability of ionic solids is generally due to the?
- A. negative electron affinity of most atoms
- B. crystal lattice forces
- C. electron pair sharing
- D. positive ionization potentials
In the oil drop experiment, Millikan determined the?
- A. charge to mass ratio of the electron
- B. mass of the electron
- C. charge of the electron
- D. mass of the proton
A particle that contains 8 proton, 9 neutrons and 7 electrons could be written as?
- A. O
- B. O+
- C. N
- D. O-
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
- D. its volume is sightly increased
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 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?
- A. 3:1
- B. 5:2
- C. 5:4
- D. 8:3
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
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
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