Q. How many kinds of rays fo radioactive elements emit?
Q. Which of the following statements about the physical properties of metals is not correct?
1) All metals are solid except mercury
2) Most of the metals are hard except sodium and potassium
3) They are not malleable
4) Hydrogen and chlorine
Q. All of the following are units of electrical measurements, except
Q. All of the following are ores of copper, except
3) Copper pyrites
Q. All of the following noble gases are present in the atmosphere, except
Q. Which of the following statements about the physical properties of nonmetals is not correct?
1) They are not ductile
2) Most of these have high melting and boiling points
3) They do not conduct electricity
4) They are not malleable
Q. The combustible material on the tip of a safety match stick is
1) Antimony sulphide
3) Manganese dioxide
Q. Which of the following factors influences the rate of chemical reactions?
1) Concentration of reactants
2) Persence of a catalyst
4) All of these
Q. Alloys, in which mercury is one of the metals, are called
Q. Which of the following is correctly matched?