Physical changes are changes affecting the form of a chemical substance, but not its chemical composition. Physical changes are used to separate mixtures into their component compounds, but can not usually be used to separate compounds into chemical elements or simpler compounds.

Ex: cutting a paper, gaining weight, cutting hair

8 0

3 years ago

Which statement correctly describes an atom of the element helium? (9)

Luden [163]

C. An atom of helium has its valence electrons in its first energy level, it wouldn't and can't satisfy the Octet rule as it only has 2 electrons, but with 2, it has a full shell, as the first energy level can hold only 2 electrons.

8 0

3 years ago

Liquid A is known to have a lower surface tension and lower viscosity than Liquid B. Use these facts to predict the result of be

Korvikt [17]

Answer: Option (B) is the correct answer.

Explanation:

Surface tension is defined as the attractive forces experienced by the surface molecules of a liquid by the molecules present beneath the surface layer of the liquid.

And, viscosity is defined as the ability of a liquid to resist its flow. When a substance has high viscosity then it is known as a viscous substance.

Since, it is given that viscosity of liquid B is more than liquid A. Therefore, liquid B has more resistive force on its surface as compared to liquid A. As a result, time taken by liquid B is more than time taken by liquid A.

Also, Surface tension = $\frac{Force}{Length}$

Surface tension of liquid B is more than liquid A. Therefore, $F_{B} > F_{A}$ .

Thus, we can conclude that tA will be less than tB.

8 0

3 years ago