Q11-German silver is an alloy of
Ans-zinc, copper, and nickel
Q12.What is the name of that system, which uses radioactivity to decide the period of materials of-pre-his-toric period?
Q13.What happens when a chemical bond is formed?
Ans-Energy is always absorbed
Q14.Where does the oxygen that keeps us alive come from?
Q15.What is the chemical name for ‘baking soda’?
Q16.Who developed Hydrogen Bomb?
Q17.Who developed atom bomb?
Ans-J. Robert Oppenheimer
Q18.What is the most commonly used substance in fluorescent tubes?
Ans-Mercury vapor and argon
Q19.What is “milk magnesia” chemically?
Q20.Diamonds are glittering and attractive because light incident on them undergoes
Ans-Multiple internal reflections