Answer - Its atomic number is 2, so it has two protons in its nucleus. Its nucleus also contains two neutrons. Since 2 + 2 = 4, we know that the mass number of the helium atom is 4.
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No as oxygen is not balance
In reactants side there is 12 oxygen and in the product side there is 8 oxygen
Wear a chemical-resistant apron, chemical-resistant gloves and chemical splash goggles at all times when handling HCl to protect your eyes and skin. Concentrated hydrochloric acid is toxic if inhaled, so avoid breathing it in and always handle it while under a fume hood.