Answer: D) helium.
Explanation:
Nuclear fission is a process which involves the conversion of a heavier nuclei into two or more small and stable nuclei along with the release of energy.

Nuclear fusion is a process which involves the conversion of two small nuclei to form a heavy nuclei along with release of energy.
Example: 
Thus when deuterium and tritium , the two isotopes of hydrogen are fused, a heavier nuclei helium is being formed from two smaller nuclei releasing a neutron.
Answer:
cools as it rises, then sinks back down
Explanation:
The movement of air is a convection current. Convection currents occur when warm air rises, cools down, and sinks due to gained density, replacing the warm air closer to the ground, creating a cycle.
Answer:
false
Explanation:
false, only a small percentage of mutations cause genetic disorders—most have no impact on health or development. For example, some mutations alter a gene's DNA sequence but do not change the function of the protein made by the gene.
Answer:
The following are some ways of safely disposing of non-biodegradable waste.
1. Take them to a local recycling facility. Separate metal, plastic, glass, and other non-biodegradable waste and store them ready for recycling.
2. Combustion and energy recovery.
3. Disposal at sanitary facilities.
4. Reduce.
5. Landfills.
Explanation: Hope it helps! ^_^"
(G00gle)
Answer: D. 19.9 g hydrogen remains.
Explanation:
To calculate the moles, we use the equation:
a) moles of
b) moles of
According to stoichiometry :
1 mole of
require 1 mole of
Thus 0.0787 moles of
require=
of
Thus
is the limiting reagent as it limits the formation of product and
acts as the excess reagent. (10.0-0.0787)= 9.92 moles of
are left unreacted.
Mass of
Thus 19.9 g of
remains unreacted.