1%
Explanation:
The crust is the thinnest layer of the earth accounting for only 1% total volume of the planets.
Compositionally, the earth is divided into three layers which are the crust, mantle and the core.
- The crust is the outermost layer of the earth. It rich in silicate minerals. The rocks are classified into igneous, sedimentary and metamorphic rocks.
- The mantle takes up about 84% of the total volume of the earth. It is located in between the crust and the core. It is predominantly made up of ferro-magnesian silicate minerals.
- The cores accounts for slightly 15% of the volume of the earth. It is the center of our geoid shaped earth. It is rich in iron and nickel metals.
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Water acts as an acid (donates H+) when it reacts with a stronger base, say sodium hydroxide. Water acts as a base (accepts H+) when it reacts with a stronger acid, say hydrochloric acid. If the medium is water, water, having a pH of 7, is considered neutral.
Answer: The periodic table
Explanation: Demetri Mendeleyev is famous for developing the periodic table. He introduced it in 1869.
Answer:
2Al(s) +3Ni²⁺(aq) ⟶ 2Al³⁺(aq) + 3Ni(s)
Explanation:
The unbalanced equation is
Al(s) + Ni²⁺(aq) ⟶ Ni(s) + Al³⁺(aq)
(i) Half-reactions
Al(s) ⟶ Al³⁺(aq) + 3e⁻
Ni²⁺(aq) + 2e⁻ ⟶ Ni(s)
(ii) Balance charges
2 × [Al(s) ⟶ Al³⁺(aq) + 3e⁻]
3 × [Ni²⁺(aq) + 2e⁻ ⟶ Ni(s)]
gives
2Al(s) ⟶ 2Al³⁺(aq) + 6e⁻
3Ni²⁺(aq) + 6e⁻ ⟶ 3Ni(s)
(iii) Add equations
2Al(s) ⟶ 2Al³⁺(aq) + 6e⁻
<u>3Ni²⁺(aq) + 6e⁻ ⟶ 3Ni(s) </u>
2Al(s) +3Ni²⁺(aq) + <em>6e</em>⁻ ⟶ 2Al³⁺(aq) + 3Ni(s) + <em>6e⁻
</em>
Simplify (cancel electrons)
2Al(s) +3Ni²⁺(aq) ⟶ 2Al³⁺(aq) + 3Ni(s)
