Explanation:

When goods worth Rs.50 are given as charity, it means the company has made a donation. Donations are not a regular business transaction for which the company would use the sales or purchase account. The correct account to credit in this case is the Charity account.

Charity Account:
Charity account is a nominal account that records donations or contributions made by the company. These contributions could be in the form of cash, goods, or services. The Charity account is credited whenever the company makes a donation or contribution.

Sales Account:
The sales account is used to record revenue earned by the company from the sale of goods or services. When the company sells goods or services, the sales account is credited. However, in the case of charity, the company is not earning any revenue, but instead, it is giving away goods as a donation. Hence, the sales account is not applicable here.

Purchase Account:
The purchase account is used to record the cost of goods purchased by the company. When the company buys goods, the purchase account is debited. However, in the case of charity, the company is not purchasing any goods, but instead, it is giving away goods as a donation. Hence, the purchase account is not applicable here.

Cash Account:
The cash account is used to record cash transactions. When the company makes a donation in the form of cash, the cash account is credited. However, in the case of charity, the company is not making a cash donation, but instead, it is giving away goods as a donation. Hence, the cash account is not applicable here.

Conclusion:
In conclusion, when goods worth Rs.50 are given as charity, the correct account to credit is the Charity account, as it records donations made by the company.