If the change in free energy of a system is -899 Jmol-1 and the entropy change is 10Jmol-1k-1 at 250C, calculate the enthalpy change.
- A. +2081 Jmol-1
- B. -2081 Jmol-1
- C. -649 Jmol-1
- D. +649 Jmol-1
How many faraday of electricity is required to produce 0.25 mole of copper?
- A. 1.00F
- B. 0.01F
- C. 0.05F
- D. 0.50F
Calculate the quantity of electricity in coulombs required to liberate 10g of copper from a copper compound
[Cu=64, F = 96500 Cmol-1]
- A. 32395.5
- B. 30156.3
- C. 60784.5
- D. 15196.5
\(H_2O_{(g)} + C_{(s)} → H_{2(g)} + CO_{(g)}\)
The oxidizing agent in the reaction above is
- A. CO(g)
- B. C(s)
- C. H2O(g)
- D. H(2)(g)
Zn (s) + CuSO 4(aq) → ZnSO 4(aq) + Cu (s)
In the reaction above, the oxidation number of the reducing agent changes from
- A. 0 to + 4
- B. 0 to + 2
- C. + 1 to + 2
- D. + 1 to + 3
Which of the following salts will turn blue litmus red?
- A. Sodium tetrahydroxozincate (ll)
- B. Sodium hydrogentetraoxosulphate (VI)
- C. Sodium trioxocarbonate (lV)
- D. Zinc chloride hydroxide
The mathematical expression of PH is
- A. log 10[OH-]
- B. log 101/[H 3 O+]
- C. log 10[H 3 O+]
- D. log 101/[OH -]
The colour of litmus in a neutral medium is
- A. purple
- B. pink
- C. yellow
- D. orange
The major and most effective way of controlling pollution is to
- A. improve machinery so that the substances released from combustion are less harmful
- B. pass strict laws against it by individuals and companies
- C. educate people on the causes and effects of pollution
- D. convert chemical wastes to harmless substances before releasing them into the environment
The dispersion of a liquid in a liquid medium will give
- A. an emulsion
- B. a fog
- C. a gel
- D. an aerosol
16.55g of lead (ll) trioxonitrate (V) was dissolved in 100g of distilled water at 20oC, calculate the solubility of the solute in moldm-3
[Pb = 207, N = 14, O = 16]
- A. 0.05 g
- B. 2.00 g
- C. 1.00 g
- D. 0.50g
On exposure to the atmosphere, a hydrated salt loses its water of crystallization to become anhydrous. This phenomenon is referred to as
- A. efflorescence
- B. deliquescence
- C. hygroscopy
- D. hydrolysis
Water is said to be temporarily hard when it contains
- A. Ca (HCO3)2 and Mg (HCO3)2 salts
- B. Ca (HCO3)2 and CaCO3 SALTS
- C. Mg(HCO3)2 and CaSO4 salts
- D. CaSO4 and Ca(HCO3)2 salts
A silicon -containing ore has 92% 28Si, 5% 29Si and 3% 30Si. Calculate the relative atomic mass of the silicon.
- A. 14.00
- B. 29.00
- C. 28.11
- D. 28.00
The radio active radiation used in studying the arrangement of particles in giant organic molecules is
- A. \(\gamma\)- rays
- B. \(\alpha\)- particles
- C. X-rays
- D. \(\beta\) - particles
How many protons, neutrons and electrons respectively are present in the element 60/27 Co?
- A. 27, 33 and 33
- B. 33, 27 and 27
- C. 27, 33, and 27
- D. 60, 33 and 60
If the difference in electronegativity of elements P and Q is 3.0. The bond that will be formed between them is
- A. metallic
- B. covalent
- C. co-ordinate
- D. ionic
Beryllium and aluminum have similar properties because they?
- A. are both metals
- B. belong to the same group
- C. belong to the same period
- D. are positioned diagonally to each other
An element X has electron configuration 1s2 2s2 2p6 3s2 3p5. Which of the following statements is correct about the element?
- A. lt has a completely filled p-orbital
- B. lt has 5 electrons in its outermost shell.
- C. lt belongs to group ll on the periodic table
- D. lt is a halogen
200 cm3 of a gas at 25ºC exerts a pressure of 700 mmHg. Calculate its pressure if its volume increase 350 cm3 at 75ºC.
- A. 342.53 mmHg
- B. 1430.54 mmHg
- C. 467.11 mmHg
- D. 400.00 mmHg