Questions

Let that something be 'x'

From the given data,

x + x/5 = 21

5x + x/5 = 21

6x = 21 x 5

=> x = 17.5

Hence, that something is x = 17.5.

National Science Day is celebrated in India on 28 February each year to mark the discovery of the Raman effect by Indian physicist Sir Chandrashekhara Venkata Raman on 28 February 1928.

The hertz (Hz) is defined as one cycle per second and is a SI unit of frequency. Here kilohertz is also a unit of frequency of waves and is defined as 1000 cycles per second. Radio waves are measured in kilohertz (KHz).

A Libraury. It has more number of story books in it to read.

Eukaryotic cells all have a nucleus. Eukaryotes are organisms that are multicellular, although there are some examples of single cellular eukaryotes. So eukaryotic cells can be either cell with a nucleus or a eukaryotic organism's cell.

The most important feature to judge whether it has nucleus membrane.

And for other choices, they are the common features of eukaryote and prokaryote.

Except pineapple remaining all three are types of apples.

Pineapple is what kind of apple isn't an apple.