MCQ Answers Chemistry 2017 A/L

1. 1
2. 3/4
3. 5
4. 5
5. 2
6. 2/3/5
7. 4
8. 4
9. 2
10. 3
11. 3
12. 2
13. 2
14. 2
15. 1/4
16. 2
17. 1
18. 2
19. 3
20. 2
21. 4
22. 1
23. 1
24. 5
25. 1
26. 4
27. 2
28. 4
29. 3
30. 4
31. 5
32. 2
33. 4
34. 5
35. 3
36. 4
37. 5
38. 5
39. 4
40. 1/5
41. 5
42. 3
43. 1
44. 3
45. 2/3
46. 3
47. 3
48. 1
49. 4
50. ALL

CHEMISTRyY Review Part-2

8. -All alkaline earth metals react with N2 gasat high temperature ( True)

    -Alkaline earth metals have high boiling points than alkaline metals. Therefore second statement is also correct.

    -Second ionization energy of alkaline metals are higher than that of alkaline earth metals. Therefore third statement is also correct.

    -Be(OH)2 and Mg(OH)2 are not strong bases as they do not dissociate completely in aqueous medium. Therefore this statement is false.

    - Down the first group solubility of their hydroxides increase. Therefore this is also true. 

     (Answer- 4)

9. Number of protons in Lithium= 3

    Effective nuclear charge is charge of nucleus felt by outer electrons. Due to electrons in 1n energy level,(they neutralize some amount of charge) charge felt by outer electrons are slightly lower than +3 (Answer – 2)

10. When some O2 is added to mixture at equilibrium some amount of O2 join with SO2 to form SO3. Therefore amount of SO2 become less than initial value when equilibrium is reestablished.  (Answer- 3)

12. Energy in 1 *10^20 photons = 6.626Js × (3×10⁸ ms^-1)

                                                              (470×10^-9  m)

                                                       = 7.1s//  (Answer- 2)

13.               ΔG = ΔH -TΔS           - Reaction is spontaneous until ΔG < 0. When temperature increase,

                                                        -If ΔS is negative (-TΔS) value increase positively.

                                                        -If ΔS is positive (-TΔS) value increase negatively.

     Therefore for ΔG to become positive from a negative value, initially ΔH, ΔS & ΔG must be negative. (Answer -2)

17. Rate constant is only dependent on temperature. Therefore no matter the concentration of reaction rate constant remain same (Answer- 1)

2017 A/L MCQ Review / CHEMISTRY

2017 A/L MCQ Review / CHEMISTRY (Part-1)

Question no

1. Atomic model proposed next to plum pudding model of J.J. Thompson was nuclear model. It was proposed by Rutherford. Therefore disproving plum pudding model was done by Rutherford.(1^st answer)

2.–Since all compounds contain more than 1 element, there should be polarizations in bonds because of electronegativity difference between atoms involved in bond. Therefore first choice is true.                                                                                                       –Shape of CO₂ is linear and that of BF₃ is trigonal planer, this proves that compounds are with different shapes. Therefore 2^nd choice is also true.                                                          Only BF₃ from given compounds do not obey octet rule (8 valence electrons in central atom after bond formation) as this is false this can be the answer.                                      BF₃ Is polar therefore, this can also be taken as an answer.                                                     Only XeF4 and BF₃ have lone pairs on central atom, therefore this statement is also true. (Answers will be 3 or 4)

3.This is an aldehyde (with CHO group). Therefore name end with suffix “al”. Only 3, 4 & 5 answers contain that suffix. Longest carbon chain in this compound include a triple bond therefore “yn” term should come before suffix. Only 5^th choice contain “yn” term. Note- “yne” term is not written in middle of a name. (Answer -5)

4.NH₂ OH is the answer. It contain 3 H. Each hydrogen is in +1 state (Total=+3) therefore N & O should collectively have -3, as no charge is on molecule. Since O is in -2 state, to make a total -3, oxidation state of N should be -1. (Answer-5)

Shapes originated from trigonal bi pyramidal shape is as follows. Bi pyramidal shape originate from 5 VSEPR pairs.  (Answer-2)