For testing compressive and tensile strength of cement, the cement mortar is made by mixing cement and standard sand in the proportions of A. 1 : 2 B. 1 : 3 C. 1 : 4 D. 1 : 6

The correct answer is A. 1 : 2.

Cement mortar is a mixture of cement, sand, and water. It is used for a variety of purposes, including laying bricks, tiles, and concrete slabs. The proportions of cement and sand in a cement mortar mix can vary depending on the desired strength and durability of the mortar.

For testing compressive and tensile strength of cement, the cement mortar is made by mixing cement and standard sand in the proportions of 1 : 2. This means that for every part of cement, there should be 2 parts of sand. This is the most common proportion used for cement mortar, and it provides a good balance of strength and durability.

The other options are not correct because they do not provide the same balance of strength and durability. Option B, 1 : 3, would result in a weaker mortar, while Option C, 1 : 4, would result in a stronger mortar. Option D, 1 : 6, would result in a very strong mortar, but it would also be very brittle.

In conclusion, the correct answer is A. 1 : 2. This is the most common proportion used for cement mortar, and it provides a good balance of strength and durability.