Questions

The most common gas people breathe from clean air is nitrogen. Air is a mixture of gases, and the air on Earth contains about 78 percent nitrogen and about 21 percent oxygen. Argon, carbon dioxide neon, helium, methane, krypton, hydrogen and xenon are in much smaller amounts.

‘Instead’ is used as an alternative or substitute and is not relevant in this context. ‘Nevertheless’ will be used as it means ‘inspite of that’. Thus, the correct formation would be, ‘This scooter is not as efficient as it used to be; nevertheless it is still a very useful machine.

According to geological history, the important mountains of india arranged in the order of age starting from the oldest are the Aravallis , the westerm Ghats, Vindhya and Satpura, the Nilgiris , and the Himalayas.

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