Explanation:
Here's an oxidation chart to help
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Answer:
OPTION (A) : Testing a rock sample for gold content
Explanation:
For testing a rock sample of gold content you will need a Chemist. To test the material, the sample is rubbed on black stone which will leave a mark on the stone. This mark is tested by applying aqua fortis i.e nitric acid on the mark. If the mark gets dissolve then the material is not gold. If the mark sustain the it is further tested by applying aqua regia i.e nitric acid and hydrochloric acid which will prove the sample is of gold if it gets dissolve on using hydrochloric acid. The purity of the sample can be checked by differing the concentration of the aqua regia and comparing it with the gold material of the known purity.
M₁ = mass of water = 75 g
T₁ = initial temperature of water = 23.1 °C
c₁ = specific heat of water = 4.186 J/g°C
m₂ = mass of limestone = 62.6 g
T₂ = initial temperature of limestone = ?
c₂ = specific heat of limestone = 0.921 J/g°C
T = equilibrium temperature = 51.9 °C
using conservation of heat
Heat lost by limestone = heat gained by water
m₂c₂(T₂ - T) = m₁c₁(T - T₁)
inserting the values
(62.6) (0.921) (T₂ - 51.9) = (75) (4.186) (51.9 - 23.1)
T₂ = 208.73 °C
in three significant figures
T₂ = 209 °C
Answer:
b) Gain or lose electrons
Explanation:
An ion is an electrically charged particle. For an atom to be charged, it must have gained or lost electron in the process and therefore, it becomes an ion.
The loss or gain of electrons is what makes an atom charged and eventually becomes an ion.
A positively charged ion is one that has lost an electron and it is called a cation. In such an ion, the number of electrons are lesser than those of protons. This is why they are cations
A negatively charged ion is one that has gained electrons. They are called anions. In such an ion, the number of electrons are greater than that of protons.
