Answer: -
A solar nebula is a rotating cloud of gas and dust from which the sun and the planets formed.
A planetesimal is a small body from which planet originated in the early stages of development of the solar system.
Kupier belt is region of the solar system that is just beyond the orbit of Neptune and that contains bodies made mostly of ice.
This is the region of the solar system that contains small bodies that are made mostly of ice.
Thus Pluto is formed from the huge disk of ice and debris beyond the outer planets. Comets originating from the Kupier belt are also composed of ice and debris.
The atomic mass on the periodic table represents the sum of number of protons and number of neutrons.
Atomic mass = Number of protons + number of neutrons
Hope this helps!
<span>Cytosine is a building block of DNA,
it is a component to DNAs base pairs and pairs with guanine (these pairs make up the rungs of its double helix)... it is not Ribose as plain Ribose has a hydroxyl group where a hydrogen atom should be if it were to be found in DNA and be deoxyribose (hence deoxyribonucleic acid and not ribonucleic acid since ribonucleic acid is RNA). Uracil is only found in RNA and actually takes Cytosine's place in the rungs of RNA and binds with guanine (although RNA is not in the conventional double helix shape and more resembles a protein in shape). Polypeptide is a long peptide chain and usually associated with proteins and not DNA....</span>
<u>Answer:</u> The percent composition of hydrogen in the sample is 15.22 %
<u>Explanation:</u>
We are given:
Mass of hydrogen = 7 grams
Mass of nitrogen = 32 grams
Mass of carbon = 7 grams
Total mass of the sample = 7 + 32 + 7 = 46 grams
To calculate the percentage composition of hydrogen in sample, we use the equation:

Mass of sample = 46 g
Mass of hydrogen = 7 g
Putting values in above equation, we get:

Hence, the percent composition of hydrogen in the sample is 15.22 %
Answer :
(a) displacement reaction
(b) combination reaction
(c) disproportionation reaction
(d) displacement reaction
Explanation :
(a) The given balanced chemical reaction is,

This reaction is a single replacement reaction or displacement in which the the more reactive element (Fe) replace the less reactive element (H).
(b) The given balanced chemical reaction is,

This reaction is a combination reaction in which the two reactants molecule combine to form a large molecule or single product.
(c) The given balanced chemical reaction is,

This reaction is a disproportionation reaction in which the chemical species gets oxidized and reduced simultaneously. It is also considered as a redox reaction.
(d) The given balanced chemical reaction is,

This reaction is a single replacement reaction or displacement in which the the more reactive element (Ag) replace the less reactive element (Pt).