GATE Questions

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Gene is a hereditary unit consisting of a sequence of DNA that occupies a specific location on a chromosome and determines a particular characteristic in an organism.

In short it is a piece or segment of chromosome.

Genes undergo mutation when their DNA sequence changes. 

When two or more chemical species combine to form a single product, the reaction is said to be synthesis reaction. It is also called as Direct Combination reaction.

Here in the given options, Sodium (Na) combines with Chlorine (Cl) to form a more complex single product Sodium Chloride (NaCl).

Therefore the answer for What travels around the world but stays in one spot is STAMP or any other thing that acts as a stamp does.

Ex. the letter in the envelope etc...

Since, Several things have the possibility, but the word travel evokes that it would move. 

Frequency is what means how many times the event occurs in the same period.

According to 2018 January reports, Mukesh Ambani is the first richest person in India being 18th in the world, followed by Azim Premji and S.P. Hinduja in second and third places.

Agriculture would be a good example of a purely competitive industry.

The device which is used to measure air pressure is called as barometer. If the barometer reading is rising, it indicates that the air pressure is increasing and if the reading is falling the air pressure is decreaing.