Answer:
Na₂CO₃.2H₂O
Explanation:
For the hydrated compound, let us denote is by Na₂CO₃.xH₂O
The unknown is the value of x which is the amount of water of crystallisation.
Given values:
Starting mass of hydrate i.e Na₂CO₃.xH₂O = 4.31g
Mass after heating (Na₂CO₃) = 3.22g
Mass of the water of crystallisation = (4.31-3.22)g = 1.09g
To determine the integer x, we find the number of moles of the anhydrous Na₂CO₃ and that of the water of crystallisation:
Number of moles = 
Molar mass of Na₂CO₃ =[(23x2) + 12 + (16x3)] = 106gmol⁻¹
Molar mass of H₂O = [(1x2) + (16)] = 18gmol⁻¹
Number of moles of Na₂CO₃ = 
= 0.03mole
Number of moles of H₂O = 
= 0.06mole
From the obtained number of moles:
Na₂CO₃ H₂O
0.03 0.06
Simplest
Ratio 0.03/0.03 0.03/0.06
1 2
Therefore, x = 2
The light reflected from the surface of the Moon takes only a second to reach Earth. The Sun is more than 8 light-minutes away. And so, if the light from the nearest star (Alpha Centauri) takes more than 4 years to reach us, we're seeing that star 4 years in the past.
Both Potassium and Fluorine only form one bond. Each potassium atom will donate there electron to 1 fluorine atom to form a bond. Therefore, you will need 30 Fluorine atoms.
Explanation:
According to https://oureverydaylife.com/lemon-juice-stop-apples-browning-21624.html it days that"
Chemical Reaction
Once added to sliced apples, the ascorbic acid, or vitamin C, in lemon juice creates a barrier between the oxygen and the polyphenol oxidase. Until the lemon juice has evaporated or been completely absorbed, the oxygen reacts with the ascorbic acid, preventing the apple from turning brown".
The answer to this one is brittleness ! ;)
