Sunday, 24 March 2019

NDA PAST QUESTIONS ON CHEMISTRY 2015


1. The apparatus used in the industrial separation of crude oil into its various fractions
A. Lieber condenser
B. Delivery Tower
C. Petroleum Tower
D. Fractionating tower

2. Which of the following statements is not correct about group VII elements? They are
A. diatomic
B. with relatively low ionizing potential
C. have a high electron affinity
D. good oxidizing agents


3. Which of the following molecules has two lone pairs of electrons and is 5P3 hybridised?
A. NH3
B. C6H6
C. H2O
D. CO2

4. What is the half-life of a radioactive nuclide whose decay constant is 0.0522yr-1
A. 0.03 yr
B. 0.30 Yr
C. 0.70 Yr
D. 13.30 Yr

5. In the reaction 4NH3(g) + 5O2(g) 4NO(g) + 6H2O, 1.0mol of ammonia and 1.0mol of oxygen are made to react. Therefore,
A. 1.0 mol of H2O will be produced
B. 1.0 mol of NO will be produced
C. all the ammonia will be consumed
D. oxygen will be the limiting factor

6. Steam changes the colour of anhydrous cobalt (II) chloride from
A. blue to pink
B. white to blue
C. white to red
D. blue to white

7. The electronic configuration of excited carbon atom is
A. 1S22S22Px12Py1
B. 1S22S22Px12Py12Pz1
C. 1S22S22P2
D. 1S22S12P4

8. For the reaction: 2H+ + Zn H2 + Zn2+
 G = —147KJmol. What is the corresponding value of E° cell?
A. 1.52V
B. —0.76V
C. 0.76V
D. —1.52V

9. The atomic number of Iron is 26. What is the number of unpaired electrons in Fe3+1
A. 5
B. 4
C. 3
D. 2

10. Baking soda and hydrochloric acid react according to the following equation:
NaHCO3(aq) + HCl(aq) NaCl(aq) + CO2(g) + H2O(g) Calculate the mass of baking soda (NaHCO3) that would produce 10.0g of carbon (IV) oxide [Cl = 35.5, Na 23.0 O = 16, C = 12 H = 1]
A. 19.0g
B. 38.0g
C. 190.0g
D. 320.0g

11. What is the main gas found in the air we breathe?
A. Oxygen
B. Carbon dioxide
C. Nitrogen
D. Methane

12. What is the first most abundant element in the universe in terms of mars
A. Carbon
B. Hydrogen
C. Oxygen
D. Copper

13 The most common bleaching agent is?
A. Alcohol
B. Carbon dioxide
C. Chlorine
D Caustic soda

14. The law which states that the amount of gas dissolved in a liquid is proportional to its partial pressure is'?
A. Dalton's law
B. Gay Lussac's law
C. Henry's Law
D. Raoult's Law

15. Which is the chemical formula for Iron (III) sulphate
A. Fe2SO4
B. Fe3SO4
C. Fe(SO4)3
D. Fe2(SO4)3

16. NH4Cl(s) NH3(g) + HCl(g)
The reaction above can only attain equilibrium if?
A. It is in a closed system
B. It is in an open system
C. a gaseous reactant is added
D. one of the product is removed

17. For elements in the left-most column of the Periodic Table, properties that have increasing values as the atomic number increases, include which of the following?
I
Ionization Energy (Potential)
II
Atomic radius
III
Atomic mass

A. I only
B. III only
C. I and II only
D. II and III only

18. The number of oxygen atoms in 0.50 Mole of KHSO4 is
A. 1.2 X 1023
B. 2.4 x 1024
C. 3.0 x 1023
D. 1.2 x 1024

19. Which of the following is not a separation technique?
A. Sieving
B. Dissolution
C. Filtration
D. Floatation

20. An increase in the rate of a chemical reaction on heating is due to an increase in
A. Entropy
B. Enthalpy
C. Collision rate
D. Reactant concentration

21. Calculate the mass of solute in 50cm3 of 0.25mnm-3 sodium trioxocarbonate (IV)
(Na = 23, C= 12, O = 16).
A. 1.325g
B. 5.30g
C. 0.27g
D. 3.0g

22. Sulphur oxide is prepared by the action of cone H2SO4 on copper. The gas SO2 produced is moist and is dried by passing the gas_____
A. Over dilute HCl
B. Over CaO
C. Over Concentrated H2SO4
D. Under Concentrated HNO3

23. Select the equation representing the action of steam on red hot iron.
A. Fe + H2O FeO + H2
B. 2Fe + 3H2O FeSO3 + H2
C. 3Fe + 4H2O Fe(OH)3 + H2
D. 3Fe + 4H2O Fe3O4 + 4H2O

24. Nitrogen is very uncreative because
A. Much energy is needed to break the bond between the two Nitrogen atoms in the molecules
B. Less energy is needed to break the bond between the two Nitrogen atoms in the molecules
C. Of the electrovalent bond between the two atoms
D. Of the covalent bond between the two atoms.

25. Calculate the mass of trioxonitrate (V) acid necessary to react with 10g of Lead Oxide and the mass of Lead trioxonitrate (V) salt formed in the (Pb = 207, N = 14, O = 16, H = 1)
A. 6.55g
B. 5.65g
C. 14.8g
D. 0.565g

26. X has an empirical formula C2H5, and relative molecular mass 58. X is
A. Ethane
B. Propane
C. Butane
D. Hexane

27. The cracking of petroleum increases the yield of gasoline because it converts
A. Higher alkalis into lower alkanes and gasoline
B. Lower Alkanes and alkenes into higher alkenes
C. Alkenes into alkenes by hydrogenation
D. Alkenes into alkanol by hydration

28. what is the pH of 0.01 M hydrochloric acid solution?
A 2
B. 3
C. 6
D. 5

29. Aqua-regia is a mixture of_____
A. One part of conc. HNO2 and one part of conc. HCl
B. Three parts of conc. HNO3 and one part of conc. HCl
C. Two parts of conc. HNO3 and one part of conc. HCl
D. Two parts of conc. HNO3 and three part of conc. HCl

30. Graphite conducts electricity because?
A. it is crystalline
B. it contains an excess of electrons
C. contains an excess of electrons
D. its atoms are close together

31. Which of the following compounds is composed of Al, Si, O and H?
A. Epsom salt
B. Limestone
C. Clay
D. Urea

32. The nucleus of an atom consists of
A. electrons and neutrons
B. electrons and protons
C. proton and neutrons
D. All of the above

33. What is the advantage of an alloying lead with tin?
A. melting point is increased
B. workability is reduced
C. the alloy is used in joining metals
D. the alloy is a catalyst in iron on extraction

34. Which of the following statement is correct about Osmotic Pressure
A. It is the pressure required to prevent a solute flowing across a semi-permeable membrane from high to low region of concentration.
B. It is the pressure required to allow a solvent flowing across a semi-permeable membrane from high to low region of concentration.
C. It is the pressure required to prevent a solvent flowing across a semi-permeable membrane from a region of high to low region of concentration.
D. It is the pressure required to prevent a solvent flowing across a semi-permeable membrane from a region of low to a high region of concentration.

35. In the Haber process for the manufacture of ammonium, the catalyst commonly used is finely divided
A. vanadium
B. platinum
C. iron
D. copper

36. A mixture of sand, ammonium chloride and sodium is best separated by
A. sublimation followed by addition of water and filtration
B. sublimation followed by addition of water and evaporation
C. addition of water followed by filtration and sublimation
D. addition of water followed by crystallization and sublimation

37. The densities of two gases, X and Y, are 0.5g dm3 and 2.0g dm-3 respectively. What is the rate of diffusion of X relative to Y?
A. 0.1
B. 0.5
C. 2.0
D. 4.0

38. The number of electrons in the valence shell of an element of atomic number 14 is
A. 1
B. 2
C. 3
D. 4

39. A solid that absorbs water from the atmosphere and forms an aqueous solution is
A. hydrophilic
B. efflorescent
C. deliquescent
D. hygroscopic

40. How many moles of HCl will be required to react with potassium heptaoxodichromate (VI) to produce 3 moles of chlorine?
A. 14
B.12
C. 11
D. 10

ANSWERS:

1. D
2. B
3. C
4. D
5. D
6. A
7. B
8. C
9. C
10. A
11. C
12. B
13. C
14. C
15. D
16. A
17. D
18. D
19. D
20. C
21. A
22. B
23. A
24. A
25. B
26. C
27. A
28. A
29. D
30. B
31. C
32. C
33. A
34. B
35. C
36. A
37. C
38. D
39. C
40. A