Each isotope of Oxygen has a different number of neutrons
<h3>Further explanation
</h3>
The elements in nature have several types of isotopes
Atomic mass is the average atomic mass of all its isotopes
Isotopes are atoms has the same number of protons but has a different number of neutrons.
So Isotopes are elements that have the same Atomic Number (Proton)
Some of the isotopes of oxygen are:

Each isotope has 8 protons and 8 electrons but has a different number of neutrons
For O-16: number of neutrons = 16-8 = 8
For O-17: number of neutrons = 17-8 = 9
For O-18: number of neutrons = 18-8 = 10
Answer:
B
Explanation:
Ethanol is C2H6O. Carbon diozidex is CO2. Ethanol has hydgrogen, where carbon dioxide does not.
Answer:
(a)
(b) 
Explanation:
The reaction that is carried out by the enzyme catalase produces
The reaction that is carried out by the enzyme catalase produces 
The reaction between mercury (Hg) and sulfur (S) to form HgS is:
Hg + S ------------- HgS
Therefore: 1 mole of Hg reacts with 1 mole of S to form 1 mole of HgS
The given mass of Hg = 246 g
Atomic mass of Hg = 200.59 g/mol
# moles of Hg = 246 g/ 200.59 gmol-1 = 1.226 moles
Based on the reaction stoichiometry,
# moles of S that would react = 1.226 moles
Atomic mass of S = 32 g/mol
Therefore, mass of S = 1.226 moles*32 g/mole = 39.23 g
39.2 g of sulfur would be needed to react completely with 246 g of Hg to produce HgS
Answer:
A. predation.
Explanation:
Predation is a type of ecological interaction in which one organism which is known as predator feeds upon another organism thereby killing it. The organism which is killed by predator is known as prey. In such interaction one organism is benefited while another one is harmed.
Brown bears of Alaska feed upon salmon. In order to so they have developed many ways which include waiting at the bottom of falls from where salmons pass by or standing at the bottom of the falls.