Which of the following is not correct about oxidation number convention? The oxidation number of a/an
- A. element in the free state is zero
- B. monatomic ion is equal to its charge
- C. alkali meta like sodium in its compounds is + 1
- D. atom of a diatomic molecules is + 2
What will be the effect of increase in pressure on the following system at equilibrium? 2NH2(g) N2(g) + 3H2(g)
- A. Activation energy will decrease
- B. the forward reaction will be favoured
- C. the concentration of ammonia will increase
- D. the reaction will go to completion
Consider the reaction represented by the following equation: H2(g) + 12(g) → 2HI(g). The number of effective collisions of molecules of the reactants decreases as
- A. the temperature is raised
- B. the pressure increased
- C. the volume of the system is increased
- D. a catalysty is intoduced into the system
Which of the following lowers the activation energy of a chemical reaction?
- A. Freezing mixture
- B. Reducing agent
- C. Water
- D. Catalyst
The property of calcium chloride which makes it useful as a drying agent is that it is
- A. ionic
- B. deliquescent
- C. a strong electrolyte
- D. a normal salt
If the solubility of KHCO3 is 0.40 mole dm-3 at room temperature , calculate the mass of KHCO3 in 100dm3 of the solution at this temperature. [KHCO3 = 100hmol
- A. 4.0g
- B. 10.0g
- C. 40.0g
- D. 100.0g
Which of the following compounds dissolves in water to form a solution with pH below 7?
- A. Sodium tetraoxosulphate (VI)
- B. Potassium hydroxide
- C. Ammonium chloride
- D. Sodium trioxocarbonate (IV)
Which of the following is an acid salt?
- A. NH4CI
- B. MgSO4 7H2O
- C. CH3COONa
- D. NaHCO3
An exothermic reaction is one which involves
- A. attainment of dynamic equilibrium
- B. loss of heat to the surrounding
- C. evolution of gas as it proceeds
- D. positive change in value of enthalpy
30cm3 pf hydrogen at s.t.p combine with 20cm3 of oxygen to form steam according to the following equation 2H2(g) + O2(g) → 2H2O(g).
Calculate the total volume of the gaseous mixture at the end of the reaction
- A. 50cm3
- B. 35cm3
- C. 30cm3
- D. 25cm3
Helium is preferred to hydrogen in filling balloons because hydrogen
- A. is inflammable
- B. is diatomic
- C. exhibits isotopy
- D. is a component of water
What volume of hydrogen is produced at s.t.p. When 2.60 g of zinc reacts with excess HCI according to the following equation? Zn(s) + 2HCI(aq) → ZnCI 2(aq) + H2(g) [Zn = 65; 1 mole of a gas occupies 22.4dm3 at s.t.p]
- A. 0.040dm 3
- B. 0.896dm 3
- C. 5.82dm 3
- D. 8.62dm 3
Gas molecules are said to be perfectly elastic because
- A. they collide without loss of energy
- B. they move about in straight lines
- C. the distances between them are negligible
- D. the volume occupied by them is negligible
Equal volumes of CO2 cnd CO at s.t.p have the same
- A. mass
- B. density
- C. rate of diffusion
- D. number of molecules
Which of the following movements can be described as random motion?
- A. wheelbarrow being pushed
- B. car travelling on a straight line
- C. Gas molecules colliding in a flask
- D. Planets going round the sun
Exhaust fumes discharged from a smoky vehicle gradually become invisible as a result of
- A. diffusion
- B. combustion
- C. absorption
- D. emission
One mole of a compound M(HCO3)2 has a mass of 162g. Calculate the relative atomic mass of M. [H = 1, C =12, O = 16]
- A. 122
- B. 101
- C. 53
- D. 40
If an element with high electron affinity combines with another element with low ionization energy the bond formed will be mainly
- A. covalent
- B. ionic
- C. dative
- D. metallic
Which of the following compounds has the highest ionic character?
- A. PCI5
- B. SiCI4
- C. AICI3
- D. KCI
The crystal layers in graphite are held together by
- A. electrostatic forces
- B. van der Waals' forces
- C. hydrogen bonds
- D. covalent bonds
Which of the following halogens is the most reactive?
- A. F2
- B. Br2
- C. l2
- D. Cl