Question

Hydrogen is lightest element, but it is not used in weather balloons
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Answer 1

Answer:

Helium gas is lighter than air, therefore, a helium balloon rises, it is known as a noble gas and is therefore not reactive. Hydrogen is also lighter than air and even lighter than helium. HOWEVER, Hydrogen is not used in balloons because it is highly explosive and flammable.

Answer 2

$\huge\underline\mathcal\purple{BTS \: EXO}$

Helium gas is lighter than air, therefore, a helium balloon rises, it is known as a noble gas and is therefore not reactive. Hydrogen is also lighter than air and even lighter than helium. HOWEVER, Hydrogen is not used in balloons because it is highly explosive and flammable.