In case of a standard hydrogen electrode

According to weight, the percentage of Hydrogen in water is

Helium is preferred to Hydrogen in air balloons because it –

Discharge of nitrogen causes –

Which one of the following catalysts is used in hydrogenation of vegetable oils?

Which of the following substances cause temporary hardness in water? 1. Mg(HCO₃)₂ 2. Ca(HCO₃)₂ 3. CaCl₂ 4. MgSO₄ Select the correct answer using the code given below.