Those are both correct! great job, keep up the good work (-:
Answer: (E) 300 bq
Explanation:
Half life is the amount of time taken by a radioactive material to decay to half of its original value.
Radioactive decay process is a type of process in which a less stable nuclei decomposes to a stable nuclei by releasing some radiations or particles like alpha, beta particles or gamma-radiations. The radioactive decay follows first order kinetics.
Half life is represented by 
Half life of Thallium-208 = 3.053 min
Thus after 9 minutes , three half lives will be passed, after ist half life, the activity would be reduced to half of original i.e. 
, after second half life, the activity would be reduced to half of 1200 i.e. 
, and after third half life, the activity would be reduced to half of 600 i.e. 
,
Thus the activity 9 minutes later is 300 bq.
The answer is number 2. That releases massive amounts of radiation and by the way, that is how atomic bombs are made to detonate.
Answer:
Carbon dioxide is a linear covalent molecule.
Carbon dioxide is an acidic oxide and reacts with water to give carbonic acid.
CO 2 + H2O ==> H2CO3
Carbon dioxide reacts with alkalis to give carbonates and bicarbonates.
CO 2 + NaOH ==> NaHCO3 (Sodium BiCarbonate )
NaHCO3 + NaOH ==> Na2CO3 (Sodium Carbonate) + H2O
Water is one of the few substances which expand in volume when frozen, compared to liquid. Usually substances condense when cooled, but at the point of freezing, when liquid water becomes solid ice, the molecules lock into a matrix in which there is more space between molecules - ice expands! This is why ice floats on liquid water.
It is this miracle which has shaped the planet and allowed life to thrive. Expansion of ice is responsible for much land-shaping erosion on land, the heaving off of boulders from mountain tops. And the floating of ice on lakes, rivers and oceans - if the frozen water was indeed more dense than liquid water, it would sink and pile up in the cold depths. There would be no life thriving under the ice, overwintering. It would all eventually freeze solid, and all the life forms with it.
