The following are the half lives of four active isotopes. Which one of the following is the most dangerous to handle?

44.The following are the half lives of four active isotopes. Which one of the following is the most dangerous to handle?

A.            3 billion years

B.            100 years

C.            0.01 minute

D.            13 days

Answer: Option C

45. The gas used for artificial ripening of green fruit is

A.            ethylene

B.            ethane

C.            carbon dioxide

D.            acetylene

Answer: Option A

46.Zone refining is used for the purification of

A.            Au          B.            Ge

C.            Ag           D.            Cu

Answer: Option B

47. The main chemical constituent of the oil of cardamom which is responsible for flavour of this oil is

A.            cineole                 B.            engenol

C.            geraniol                D.            imonene

Answer: Option A

48. The molecule which has the highest percentage of ionic character among the following is

A.            HI            B.            HF

C.            HCI         D.            HBr

Answer: Option B

49. The high reactivity of fluorine is due to

A.            its high electro negativity

B.            small size of fluorine atom

C.            availability of d-orbitals

D.            strong F - F bond

Answer: Option A

50. The iron ore magnetite consists of

A.            Fe2O3                   B.            Fe3OH4

C.            FeCO3                   D.            3Fe2O3 .. 3H2O

Answer: Option A

51.          The ionisation energy of hydrogen atom in the ground state is x KJ. The energy required for an electron to jump from 2nd orbit to 3rd orbit is

A.            5x/36

B.            5x

C.            7.2 x

D.            x/6

Answer: Option A

52. The major constituent of air is

A.            nitrogen

B.            carbon dioxide

C.            oxygen

D.            hydrogen

Answer: Option A