Questions

The Great wall is a mighty monument to the building skill of ancient China. This wall, built of stone and earth to a height of 6 metres and extending over 2400 kilometres of hills and valleys, links the east coast with the mountains of the west right across northern China. The wall was wide enough for a carriage to go through.At intervals of every few hundred metres were located watch towers for warriors. Such a large study construction must have taken decades and an army of labourers to complete it. 

Expedite means making an action fast or sooner i.e, to accomplish a work as quickly as possible.

Hence, halt means stop and it is opposite of Expedite.

Dipsomania is one word substitute for Irresistible craving for alcoholic drinks.

Sucrose is not a monosaccharide.

Monosaccharides are simple carbohydrates molecules that cannot be broken down into smaller molecules of other carbohydrates.

Glucose, galactose and fructose are examples of Monosaccharides.

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.

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.