Isotopes are atoms of the same element that differ in the number of neutrons.
Remember that all the atoms of an element have the same number of protons. So the only difference between isotopes of an element is the number of neutrons.
86 Sr means that the mass number of this isotope is 86. Also, remember that the mass number is the number of protons plus the number of neutrons.
87 Sr means that the mass number of this isotope is 87.
So, 86 Sr and 87 Sr differ 1 neutron.
Answer: 1 neutron
The nutrients that the body breaks down into basic units are carbohydrates, fats, and proteins. From carbohydrates comes glucose, your body's -- especially the brain's -- primary form of fuel; from fats we get glycerol and fatty acids, many of which are essential ingredients in hormones and the protective sheath in our brain that covers communicating neurons; and from proteins we get amino acids, which are the building blocks to lots of structures, including our blood, muscle, skin, organs, antibodies, hair, and fingernails.
Each of these nutrients travels down a different pathway, but all can eventually fuel the body's production of ATP (adenosine triphosphate), which is essentially our bodies' ultimate energy currency.
a. mol O₂=0.5
b. volume O₂ = 25 cm³
c. i. the total volume of the two reactants = 75 cm³
c. ii. the volume of nitrogen dioxide formed = 50 cm³
<h3>Further explanation</h3>
Reaction
2NO(gas) + O₂(gas) ⇒ 2NO₂ (gas)
a.
mol NO = 1
From the equation, mol ratio NO : O₂ = 2 : 1, so mol O₂ :

b.
From Avogadro's hypothesis, at the same temperature and pressure, the ratio of gas volume will be equal to the ratio of gas moles
Because mol ratio NO : O₂ = 2 : 1, so volume O₂ :

c.
i. total volume of reactants : 25 cm³+ 50 cm³=75 cm³
ii. the volume of nitrogen dioxide formed :
mol ratio NO : NO₂ = 2 : 2, so volume NO₂ = volume NO = 50 cm³
To make any substance solid, molecules must come very close to each other. Substances with weak intermolecular forces have weak bonding. Hence to make their molecules come close to each other, we must provide low temperature.