Answer:
Upper cuticle and guard cells
Answer:
Theoretical yield of hydrogen is 1.11 g
Explanation:
Balanced equation, 
As Mg remain present in excess therefore HCl is the limiting reagent.
According to balanced equation, 2 moles of HCl produce 1 mol of
.
Molar mass of HCl = 36.46 g/mol
So, 40.0 g of HCl =
of HCl = 1.10 moles of HCl
Hence, theoretically, number of moles of
are produced from 1.10 moles of HCl = 
Molar mass of
= 2.016 g/mol
So, theoretical yield of
= 
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.
</span>
<span>a. </span>

<span>
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.
</span>
The main pieces of evidence that an exothermic reaction has occurred is an increase in temperature due to the release of energy, a release of energy in the form of light, or a release of gas.
boiling point - condensation point
is the answer i would choose because it makes more scene