Chemistry

A hard substance melts at high temperature and is an insulator in both solid and in molten state. This solid is most likely to be a/ an:

In basic medium H?O? exhibits which of the following reactions?
(A) Mn²? → Mn?
(B) I? → I?
(C) PbS → PbSO?
Choose the most appropriate answer from the options given below:

The oxide that shows magnetic property is:

Given below are two statements:
Statement I: C?H?OH and AgCN both can generate nucleophile.
Statement II: KCN and AgCN both will generate nitrile nucleophile with all reaction conditions.
Choose the most appropriate option:

Match List – I with List – II:
| List – I | List – II |
| :--- | :--- |
| (a) Be | (i) Treatment of cancer |
| (b) Mg | (ii) Extraction of metals |
| (c) Ca | (iii) Incendiary bombs and signals |
| (d) Ra | (iv) Windows of X-ray tubes |
| | (v) Bearings for motor engines. |

Choose the most appropriate answer from the option given below:

Given below are two statements:
Statement I: Bohr's theory accounts for the stability and line spectrum of Li²? ion.
Statement II: Bohr's theory was unable to explain the splitting of spectral lines in the presence of a magnetic field.
In the light of the above statements, choose the most appropriate answer from the options given below:

The total number of unpaired electrons present in the complex K?[Cr(oxalate)?] is _____.

Complete combustion of 3 g of ethane gives x*10²² molecules of water. The value of x is _____. (Round off to the nearest integer).
[ Use : NA = 6.023 *10²³; Atomic masses in u: C:12.0,O:16.0; H:1.0]

2 molal solution of a weak acid HA has a freezing point of 3.885°C. The degree of dissociation of this acid is _____ * 10?³. (Round off to the nearest integer).
[ Given : Molal depression constant of water = 1.85 K kg mol?¹, Freezing point of pure water = 0°C]

2NO(g) + Cl?(g) ? 2NOCl(s)
This reaction was studied at -10°C and the following data was obtained

[NO]? and [Cl?]? are the initial concentrations and r? is the initial reaction rate. The overall order of the reaction is _____. (Round off to the nearest integer).