Archives

Assertion (A) : The metals and alloys are good conductors of electricity. Reason (R) : Bronze is an alloy of copper and tin and it is not a good conductor of electricity. Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below : (a) Both (A) and (R) are true and (R) is correct explanation of the assertion. (b) Both (A) and (R) are true but (R) is not the correct explanation of the assertion. (c) (A) is true but (R) is false. (d) (A) is false but (R) is true.

(b) Both (A) and (R) are true but (R) is not the correct explanation of the assertion. The metals and alloys are good conductors of... View Article

Assertion (A) : Ethanoic acid is also known as glacial acetic acid. Reason (R) : The melting point of pure ethanoic acid is 290 K and hence it often freezes during winters in cold climates. Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below : (a) Both (A) and (R) are true and (R) is correct explanation of the assertion. (b) Both (A) and (R) are true but (R) is not the correct explanation of the assertion. (c) (A) is true but (R) is false. (d) (A) is false but (R) is true.

(a) Both (A) and (R) are true and (R) is correct explanation of the assertion. Ethanoic acid is also known as glacial acetic acid. The melting... View Article

Identify ‘x’, ‘y’ and ‘z’ in the following reaction : 2 KClO3 (x) —- (y)—> 2 KCl (x) + O2 (z) (a) x = gas ; y = reaction condition, z = gas (b) x = solid ; y = liquid; z = gas (c) x = number of moles of KClO3 ; y = reaction condition; z = no. of molecules of oxygen. (d) x = physical state of KClO3 and KCl; y = reaction condition; z = physical state of O2 .

 (d) x =  physical  state  of  KClO3  and  KCl;  y  =  reaction  condition; z = physical state of O2. Explanation:   2KClO3(x) → (y)2KCl(x) +... View Article

Consider the following reasons for the reddish appearance of the sun at the sunrise or the sunset : A. Light from the sun near the horizon passes through thinner layers of air. B. Light from the sun covers larger distance of the earth’s atmosphere before reaching our eyes. C. Near the horizon, most of the blue light and shorter wavelengths are scattered away by the particles. D. Light from the sun near the horizon passes through thicker layers of air. The correct reasons are (a) A and C only (b) B, C and D (c) A and B only (d) C and D only

(b) B, C and D Explanation The reddish appearance of the sun at sunrise or sunset is due to the scattering of light by the molecules of air and... View Article

What is hyperthyroidism?

Hyperthyroidism (overactive thyroid) occurs when your thyroid gland produces too much of the hormone thyroxine. Hyperthyroidism can accelerate... View Article