Questions

Black surfaces are good emitters of heat. If the black surface is rough too, the emitting will be better. Shinning surfaces reflect black radiation . So if the black surface is also shining the effectiveness of emitting heat is lessened.

Gram is not a Plantation crop among the given options.

Plantation crops are known as cash crops. These crops are mostly grown at tropical and subtropical areas. These crops are grown for sale but not for local consumption. such crops include rubber, coffee, tea, various oil seeds, sugar cane,etc.

So, Gram is not a plantation crop.

August Weismann cut off the tails of mice for 21 successive generations and still they produced generation after generation of only tailed young ones. So he concluded that acquired characters are not inherited.

Here crossing is AaBbCc x AaBbCc

As it is trihybrid cross,

we know, Number of zygotes formed = 4n, where n = 3

43 = 64

Given ratio of offsprings = 1 : 6 : m : 20 : m : 6 : 1

Now,  1 + 6 + m + 20 + m + 6 + 1 = 64

34 + 2m = 64

2m = 30

=> m = 15.