Answer:
D. 25 grams
Explanation:
I think that's what the answer is
Explanation:
In an alpha emission, an alpha particle is ejected from a large nucleus. An alpha particle is simply a helium nucleus (atomic number is 2 and mass number is 4) so that means that the atomic number of the emitting nucleus decreases by 2 and its mass number decreases by 4.
The simple trick which one can consider in such problem where it is asked for positron emission is :
<span>When the atomic number goes DOWN by one and mass number remains unchanged, then a positron is emitted.
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<span>a. </span>

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Here the atomic number decreases by one.
Similarly, options b and d are eliminated.
Option c is also not the answer.
For c, Count the atomic number on left side and compare it with right side. You will see it is 9 on left and 8 on right. Atomic no. did go down by 1. But the atomic mass is changed as well.
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Answer:
22.5moles
Explanation:
using mole ratio,n(CO2)/n(o)=1/2
n(CO2)=1/2n(02)
n(CO2)=1/2×45
moles of carbon dioxide produced is 22.5moles
Answer: (Chlorine-35)
Element X is Ca
Explanation:
Number of proton plus the number of electron gives the mass number.