What's the difference between climate change and global warming?

Explanation:

Global warming is the increase of the Earth's average surface temperature due to build-up of greenhouse gases in the atmosphere. Climate change is a broader term that refers to long-term changes in climate, including average temperature and precipitation.

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Option (a) is the correct answer.

Explanation:

It is known that value of electronegativity increases when we move from left to right in a periodic table.

Since the given atoms lithium, beryllium, boron, carbon and nitrogen are all second period elements. And the value of their electronegativity are as follows.

Lithium : 0.98

Beryllium : 1.57

Boron : 2.04

Carbon : 2.55

Nitrogen : 3.04

Thus, we can conclude that lithium has the least electronegativity.