How many of the following statements is/are correct? 1. Adsorbate is that substance where adsorption takes place. 2. Lower the critical temperature of the gas, the more readily it will be adsorbed. 3. Physical adsorption is an irreversible process. 4. The amount of the gas adsorbed is directly proportional to the pressure, in all pressure region. 5. By the gas masks, the poisonous gases are removed from air by charcoal, using process of adsorption. 6. The water freed from all ions (cations and anions) is referred as mineral water. 7. Heat of adsorption is defined as the energy liberated when 1 gram of a gas is adsorbed on the solid surface. 8. The adsorption of hydrogen on charcoal is chemical adsorption. 9. Froth floatation process is an application of adsorption.