chemistry quiz

Amnong the following which one is noble gas?

• Hydrogen

• Helium

• Nitrogen

• Carbon

The submbol of elements saodium is.......

• S

• SO

• Na

• Se

The number of hydrogen present in 3 H2O is

• 3

• 2

• 9

• 6

The valancy of element Mg is

• 2

• 1

• +1

• 0

What is the molecular formula of benzen

• C6H21

• C6H12

• C5H10

• C6H6