In an electrochemical cell, polarization is caused by
- A. chlorine
- B. oxygen
- C. tetaoxsulphate (Vl) acid
- D. hydrogen
2H2O (l) + 2F2(g) → 4HF(aq) + O2(g).
In the reaction above, the substance that is being reduced is
- A. O2(g)
- B. H2O(l)
- C. F2(g)
- D. HF(aq)
An insoluble salt can be prepared by
- A. the reaction of trioxocarbonate (V) with an acid
- B. double decomposition
- C. the action of dilute acid on an insoluble base
- D. the reaction of metals with an acid
Which of the following substances is not a salt?
- A. Aluminium oxide
- B. Sodium hydrogentrioxosulphate (V)
- C. Sodium trioxocarbonate (V)
- D. Zinc chloride
Three drops of a 1.0 mol dm-3 solution of HCl was added to 20 cm3 of a solution of pH6.4. The pH of the resulting solution will be
- A. close to that of pure water
- B. less than 6.4
- C. greater than 6.4
- D. unaltered
10.0 dm3 of water was added to 2.0 mol dm-3 of 2.5dm3 solution of HCl. What is the concentration of the final solution in mol dm-3?
- A. 0.4
- B. 8.0
- C. 2.0
- D. 0.5
In a water body, too much sewage leads to
- A. a decrease in the temperature of the water which cause in death of aquatic animals
- B. an increase in the number of aquatic animals in the water
- C. an increase in the bacterial population which reduces the level of oxygen in the water
- D. a decrease in the bacterial population which increases the level of oxygen in the water
The solvent used for removing grease stain is
- A. turpentine
- B. ammonia solution
- C. ethanol
- D. solution of borax in water
An example of a hygroscopic substance is
- A. CuO (S).
- B. MgCL2(S).
- C. CaCL2(S).
- D. NaOH(S).
Steam changes the colour of anhydrous cobalt (ll) chloride from
- A. white to red
- B. blue to white
- C. blue to pink
- D. white to blue
The constituent of air that acts as a diluent is
- A. nitrogen
- B. carbon (IV) oxide
- C. noble gases
- D. oxygen
The bond formed between two elements with electron configurations 1s2 2s2 2p6 3s2 and 1s2 2s2 2p4 is
- A. metallic
- B. covalent
- C. dative
- D. ionic
Which of the following molecules is held together by hydrogen bond?
- A. CH4
- B. HBr
- C. H2SO4
- D. HF
The shape of the carbon (lV) oxide molecule is
- A. pyramidal
- B. linear
- C. angular
- D. tetrahedral
The radioisotope used in industrial radiography for the rapid checking of faults in welds and casting is
- A. carbon-14
- B. phosphorus-32
- C. cobalt-60
- D. iodine-131
What volume of carbon (ll) oxide is produced by reacting excess carbon with 10 dm3 of oxygen?
- A. 5 dm 3
- B. 20 dm 3
- C. 15 dm 3
- D. 10 dm 3
The presence of an impurity in substance will cause the melting point to
- A. be zero
- B. reduce
- C. increase
- D. be stable
An element Z, contained 90% of 168Z and 10% of Z1818 its relative atomic mass is?
- A. 16.0
- B. 16.2
- C. 17.0
- D. 17.8
An isotope has an atomic number of 17 and a mass number of 36. Which of the following gives the correct number of neutrons and protons in an atom of the isotope?
- A. Neutrons 53, Protons 17
- B. Neutrons 17, Protons 36
- C. Neutrons 19, Protons 17
- D. Neutrons 36, Protons 17
If d represents the density of a gas and K is a constant, the rate of gaseous diffusion r is related to d by the equation?
- A. r = k/√d
- B. r = kd
- C. r =k/d
- D. r = k √d
The atomic numbers of two elements X and Y are 12 and 19 respectively. The bond of these two elements is?
- A. ionic
- B. covalent
- C. Metallic
- D. co-ordinate