Answer: option D - The total number of nucleons changes.
Explanation:
Nuclear Reaction is best described as a process such as the fission of an atomic nucleus, or the fusion of one or more atomic nuclei and / or subatomic particles in which the NUMBER of PROTONS and / or NEUTRONS in a nucleus CHANGES; the reaction products may contain a different element or a different isotope of the same element.
Note that the NUCLEONS refers to ONE of the subatomic particles of the atomic nucleus, i.e. a PROTON or a NEUTRON.
So, in a Nuclear reaction, the total number of nucleons changes.
Two hydrogen and two oxygen multiply for two
The density of each half of the coin is 10.49 g/cm3
In science density is defined as the ratio of mass to volume of an object.
Density is an intrinsic property.It is not affect by the amount of substance present.
This implies that each half of the broken coin must have the same density since it it is an inherent property of every silver material.
The density of each part of the coin therefore is 10.49 g/cm3.
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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.
Time taken = 3 hours
<h3>Further explanation</h3>
Given
speed : 75 mph
distance : 225 miles
Required
time taken
Solution
An equation of constant velocity motion
d = distance = m
v = speed = m / s
t = time = seconds
Input the value :
t = d : v
t = 225 miles : 75 miles/hour
t = 3 hours
