10. What is/are true for substance and mixture?
I. Pure substance melts completely.
II. Pure substance has a varying boiling point.
III. Mixture does not melt completely.
IV. Mixture has a fixed boiling point.
A. I and II only
B. I and III only
C. II and IV only
D. I and IV only
11. What does it indicate when a sugar is heated in a test tube until it is
completely changed into a black mass and droplets of water? The sugar is
a) an
A. Compound
B. Element
C. Mixture
D. Solution
12.What substance is made by mixing two elements without being cheraically
combined?
A. Compound
B. Element
C. Mixture
D. Solution​