GATE Questions

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A regular Pentagon have 5 sides and 5 lines of symmetry. 

• The number of lines of symmetry in a regular polygon is equal to the number of sides.

Sound is a mechanical vibration and needs a medium for propagation. The higher the density of the medium, the faster the sound travels. So, sound cannot travel through vacuum.

As the sound travels faster in solids than liquids and gases, sound travels faster in the glass than Air and water.

The four bonds of carbon tetrachloride (CCl4) are polar, but the molecule is nonpolar because the bond polarity is cancelled by the symmetric tetrahedral shape. Hence, making the net dipole as zero and molecule as non-polar.

When other atoms substitute for some of the Cl atoms, the symmetry is broken and the molecule becomes polar.

A greenhouse gas is a gas in an atmosphere that absorbs and emits radiant energy within the thermal infrared range. This process is the fundamental cause of the greenhouse effect. 

Carbon dioxide is a main greenhouse gas, found in car exhaust pipes.
Methane and nitrous oxide is another type of greenhouse gas.

Oxygen is the only clean gas out there because we need it to survive. Therefore, the only gas that is not a greenhouse gas is Oxygen.

Let the speed of the slower train = p kmph

ATQ,

Speed of the faster train = (p + 6) kmph

Then,

(p + p + 6) x 5 = 160

10p + 30 = 160

10p = 130

p = 13 kmph

Then, speed of the faster train = p + 6 = 13 + 6 = 19 kmph.

Fear of places and situations that might cause panic, helplessness or embarrassment is called Agoraphobia. 

Fear of crossing road causes some panic in them and comes under Agoraphobia.