GATE Questions

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In biology, Homology is defined as any characteristic of biological organisms that is derived from a common ancestor. 

Hence, Homology is evidence of Common ancestry.

Global warming is the increase in the earth’s average temperature due to release of several greenhouse gases to the atmosphere by humans. Global warming is affecting many parts of the world.

Natural Causes include :

1. Solar Activity

2. Melting Permafrost

3. Forest Fires 

Human made causes include :

1. Deforestation

2. Overpopulation

3. Landfills

4. Mining

5. Fertilizer Use

Let speed of slower train = 2x
⇒ speed of faster train = 5x
ATQ, (150 + 200)/(2x + 5x) = 15
x = 10/3
Time required=350/[50/3–20/3]= 35 seconds

Atoms are composed of three main particles called electrons, protons and neutrons. We know that, the electrons are negatively charged particles whereas protons are positively charged and neutrons have no charge.

Hence, as the number of electrons and protons are equal and they are oppositely charged, the atom will have no charge as their charges cancel each other.

Liquid sodium is being considered as engine coolant.

False. The given statement that starting or restarting a computer is called tasking the system is not correct. 

We know that the starting or restarting a computer is called Booting the system.

Polarity :: 

The polarity of a molecule defines its other physical properties such as melting point, boiling point, surface tension, vapor pressure etc... Simply, polarity occurs when the electron distribution in a molecule is asymmetric. This results in a net dipole moment in the molecule. One end of the molecule is charged negative while the other gets a positive charge.

The polarization of a molecule greatly depends on the shape of the molecule. A diatomic molecule like HF mentioned above has no issue of shape. The net dipole moment is only due to the uneven distribution of electrons between the two atoms. However, when there are more than two atoms involved in making a bond, there are many complexities.

The water molecule is of bent shape. Therefore, when the two pair of electrons shared by oxygen with two hydrogen atoms is pulled towards oxygen, the net dipole moment results in the direction of the oxygen atom. There is no other force to cancel out the resultant dipole moment. Hence, the water molecule is highly polar.

Ammonia molecule is of a pyramid shape and the electronegative N atom pulls the electrons towards itself. The three N-H bonds are not in the same plane; hence the dipole moments created do not get canceled out. This makes ammonia a polar molecule.

However, the dipole moments sometimes get canceled due to the shape of the molecules, making the molecule non-polar. Carbon dioxide is such a molecule.