Mass of the water : 2.23 g
<h3>Furter explanation</h3>
Heat
Q = m.c.Δt
m= mass, g
c = heat capacity, for water : 4.18 J/g° C.
ΔT = temperature
Q= 140 J
Δt = 75 - 60 = 15
mass of the water :

Nitrogen pure
carbon is mixture
Answer: -
Substance A is carbon dioxide and Substance B is oxygen.
Explanation: -
Photosynthesis reaction involves the process of conversion of light energy of the sun into chemical energy by the green chlorophyll found in plants leaves.
The chemical equation for the process is
6 CO₂ +6 H₂O → C₆H₁₂O₆ + 6O₂
As we can see Carbon dioxide CO₂ reacts with water H₂O to form glucose. Oxygen is the gaseous product formed.
Thus Substance A is carbon dioxide and Substance B is oxygen.
Effective nuclear charge is the charge felt by valence electrons of multi-electron atom taking into consideration the number of shielding electrons that surround the nucleus.
To calculate Z eff for electron we use this formula :
Z eff = Z - S where Z is the number of protons in nucleus and S is the average amount of electron density between the nucleus and electron in consideration
so Z eff = 17 - 10 (core electrons) = 7
So the correct answer is C