**Calculation of Closing Capital:**

Closing capital refers to the capital amount left in the business at the end of the accounting period. It can be calculated by subtracting the total liabilities from the total assets.

Given:
Assets on 31st March, 2020 = ₹3,00,000
Liabilities on 31st March, 2020 = ₹90,000

Closing Capital = Assets - Liabilities
Closing Capital = ₹3,00,000 - ₹90,000
Closing Capital = ₹2,10,000

Therefore, Aditi Arya's closing capital on 31st March, 2020 is ₹2,10,000.

**Calculation of Profit Earned:**

To calculate the profit earned during the year, we need to know the change in capital from the beginning to the end of the year. This can be calculated by subtracting the initial capital from the closing capital.

Given:
Initial capital on 1st April, 2019 = ₹2,00,000
Closing capital on 31st March, 2020 = ₹2,10,000

Profit earned = Closing Capital - Initial Capital
Profit earned = ₹2,10,000 - ₹2,00,000
Profit earned = ₹10,000

Therefore, Aditi Arya earned a profit of ₹10,000 during the year.

**Explanation:**

Aditi Arya started her business on 1st April, 2019 with a cash investment of ₹2,00,000. This amount represents her initial capital. Throughout the year, she conducted her business activities and accumulated assets and liabilities.

On 31st March, 2020, the total value of her assets was ₹3,00,000, which represents the value of all her business possessions including cash, inventory, equipment, etc. On the same date, her total liabilities amounted to ₹90,000, which represents the amount she owes to creditors.

To calculate her closing capital, we subtract the total liabilities from the total assets. In this case, her closing capital is ₹2,10,000. This amount represents the capital left in the business at the end of the accounting period.

To calculate the profit earned during the year, we subtract the initial capital from the closing capital. In this case, the profit earned is ₹10,000. This amount represents the net income generated by the business during the year.

It is important to note that the profit earned is the result of various factors such as sales revenue, cost of goods sold, operating expenses, etc. A detailed analysis of the financial statements can provide further insights into the sources of profit and the overall financial performance of the business.