Answer:- A.
and 
Explanations:- In general, 
In acid-base reaction the acid gives hydrogen ion and the base gives hydroxide ion and these ions combine to form water. Rest of the ions from acid and base combine to form the salt.
Nitric acid breaks to give hydrogen ion and nitrate ion. Similarly, NaOH breaks to give sodium ion and hydroxide ion. Since, hydrogen ion and hydroxide ions form water, the sodium ion and nitrate ion forms the salt, sodium nitrate.
The reaction is shown as:

So, the right choice is A.
Answer:
0.25 g of U-235 isotope will left .
Formula used :
where,
N = amount of U-235 left after n-half lives = ?
= Initial amount of the U-235 = 1.00 g
n = number of half lives passed = 2
0.25 g of U-235 isotope will left .
Answer:
two electrons
Explanation:
Calcium atoms will lose two electrons in order to achieve the noble gas configuration of argon.
The heat absorbed to raise temperature : Q = 31350 J
<h3>Further explanation
</h3>
Given
m = mass = 150 g
Δt = Temperature difference : 50 °C
Required
Heat absorbed
Solution
Heat can be formulated
<em>
Q = m.c.Δt
</em>
The specific heat of water = c = 4.18 J/g °C
Input the value :
Q = 150 x 4.18 x 50
Q = 31350 J