Step 1: Understand the chemical composition of foam-type fire extinguishers.
Foam fire extinguishers use a mixture of chemicals that react to form foam, which helps to suppress fires by isolating the fire from the oxygen supply.
Step 2: Identify the chemicals in foam extinguishers.
(D) NaHCO$_3$ (sodium bicarbonate) and Al$_2$SO$_4$ (aluminum sulfate) are the chemicals involved in foam generation for fire extinguishing purposes.
An electricity utility company charges ₹7 per kWh. If a 40-watt desk light is left on for 10 hours each night for 180 days, what would be the cost of energy consumption? If the desk light is on for 2 more hours each night for the 180 days, what would be the percentage-increase in the cost of energy consumption?