Answer:
A- Energy from sunlight becomes glucose during photosynthesis
Explanation:
The law of conservational photosynthetic energy states that atoms cannot be created nor destroyed; the atoms can only be rearranged into new molecules and ions. This implies that the enzymes in photosynthesis are aided by energy to transform into glucose, which the plant needs.
Answer is: P (phosphorus).
Magnesium form cation Mg²⁺, Mg lost 2 electrons, ionic radius decreases.
Aluminium form cation Al³⁺, lost 3 electron, radius decreases.
Phosphorous can form the phosphide anion P³⁻, gain 3 electrons, ionic radius increases.
Sulfur can form anion S²⁻, gain 2 electrons, but have one proton more than phosphorus, so smaller radius.
Answer:
A 0.001 molar solution of weak acid has a pH = 4.0,The pKa is :
B. 5
Explanation:
pH = It is negative logarithm of hydrogen ion concentration.
pH = -log([H+])
Ka = It is the dissociation constant.
pKa = -log(Ka)
<u>The acid dissociates according to the equation given below:</u>
![HA(aq)\rightleftharpoons H^{+}(aq)+A^{-}(aq)](https://tex.z-dn.net/?f=HA%28aq%29%5Crightleftharpoons%20H%5E%7B%2B%7D%28aq%29%2BA%5E%7B-%7D%28aq%29)
![K_{a}=\frac{[H^{+}][A^{-}]}{[HA]}](https://tex.z-dn.net/?f=K_%7Ba%7D%3D%5Cfrac%7B%5BH%5E%7B%2B%7D%5D%5BA%5E%7B-%7D%5D%7D%7B%5BHA%5D%7D)
Here , The concentration of A- and H+ will be same
So,
[H+] = [A-].....(1)
Now ,
pH = 4.0
pH = -log([H+])
4.0 = -log([H+])
- 4.0 = log([H+]) take antilog both side::"use scientific calculator"
![[H+]=10^{-4}](https://tex.z-dn.net/?f=%5BH%2B%5D%3D10%5E%7B-4%7D)
From equation (1), [A-] =
![[H+]=[A^{-}]=10^{-4}](https://tex.z-dn.net/?f=%5BH%2B%5D%3D%5BA%5E%7B-%7D%5D%3D10%5E%7B-4%7D)
[HA] = 0.001 M (given)
Insert the value of HA , H+ and A- in Ka
![K_{a}=\frac{[H^{+}][A^{-}]}{[HA]}](https://tex.z-dn.net/?f=K_%7Ba%7D%3D%5Cfrac%7B%5BH%5E%7B%2B%7D%5D%5BA%5E%7B-%7D%5D%7D%7B%5BHA%5D%7D)
![Ka=\frac{10^{-4}\times 10^{-4}}{0.001}](https://tex.z-dn.net/?f=Ka%3D%5Cfrac%7B10%5E%7B-4%7D%5Ctimes%2010%5E%7B-4%7D%7D%7B0.001%7D)
![Ka=\frac{10^{-8}}{0.001}](https://tex.z-dn.net/?f=Ka%3D%5Cfrac%7B10%5E%7B-8%7D%7D%7B0.001%7D)
![Ka=10^{-5}](https://tex.z-dn.net/?f=Ka%3D10%5E%7B-5%7D)
pKa = -log(Ka)
![pKa = -log(10^{-5})](https://tex.z-dn.net/?f=pKa%20%3D%20-log%2810%5E%7B-5%7D%29)
pKa = 5
Answer:
1. CO₂ → C + O₂
2. Fe₂ + O₂ → 2FeO
3. 2Al + 3CuO→ Al₂O₃ + 3Cu
Explanation:
1. 1 mol of CO₂ decomposes to 1 mol of C and 1 mol of oxygem
2. 1 mol of Fe₂ reacts with 1 mol of oxygen to produce 2 moles of iron (II) oxide
3. 2 moles of Al, reacts with 3 moles of cupper(II) oxide to produce 1 mol of aluminum dioxide and 3 moles of cupper