The major ingredient of leather is:
A). Collagen
B). Carbohydrate
C). Polymer
D). Nucleic acid
1. Which of the following is used to remove ink and rust stains on cloth?
2. About how much blood is in the circulatory system of an average person?
3. An electric iron has a heating element made of:
4. Sodium metal is kept under:
6. Silver halides are used in photographic plates because they are
7. The natural source of hydrocarbon is
10. The residue left after extracting juice from sugar beet and sugarcane is called