Which layer of the atmosphere contains the ozone layer that absorbs harmful ultraviolet radiation?

Which device converts sound waves into electrical signals for recording or amplification?

Which astronomical event marks the day with nearly equal hours of day and night worldwide?

Which acid in the stomach helps in the digestion of food and kills harmful bacteria?

Which part of the human eye controls the amount of light entering it?

Which cell organelle is primarily responsible for breaking down waste materials and cellular debris?

Which human body system is primarily responsible for fighting infections and diseases?

Which common household chemical is produced when electricity is passed through brine in a process called chlor-alkali?

Which everyday material is a poor conductor of heat and is commonly used as cookware handles?

Which vitamin deficiency causes pellagra characterised by dermatitis diarrhoea and dementia?

Which gas is commonly used to fill balloons so that they float in air?