Write in is/are 1.How much ________ the trousers? 2. How much ________ these shorts? 3. How much ________ a pair of socks?

1.How much are the trousers? 2. How much are these shorts? 3. How much is a pair of socks? 4. How much is this scarf? 5. How much is this dress? 6. How much are the jeans?

Trousers, shorts, jeans - существительные, которые всегда употребляются во множественном числе.