Question

HELP PLZ ITS A TEST.

Answer 1

Answer:

The answer to your question is below

Explanation:

1 ) Which of the following is a chemical property.

A. Ability to become magnetic  this is wrong, it's a physical property

B. Ability to conduct electricity   this is wrong, it's a physical property

C. Ability to conduct heat   this is wrong, it's a physical property

D. Ability to react with acid This is the right answer

2 ) You heat two substances, A and B. Both substances change color. When cooled, substance B returns to its original color, but substance A does not. What most likely happened?.

A. Physical change occurred in both substances   This is wrong, a physial change only happens in substance B

B. A physical change occurred in substance A, and a chemical change occured in substance B.  This is wrong, a physical change occurred in substance B and a chemical change occurred in substance A.

C. A chemical change occurred in substance A, and a physical change occurred in substance B.  This is the right answer is exactly what happens

D. A chemical change occurred in both substances  This answer is wrong.

3 ) how many grams are in 2.5 pound sample? Express your answer in scientific notation with three significant figures. ( 1 pound= 453.592 grams).

Rule of three

    1 pound ------------------- 453.592 g

  2.5 pounds ---------------   x

  x = 2.5(453.592)/1

  x = 1133.98 g = 1.13 x 10³ g    letter D

Answer 2

Explanation:

1).   A property that does not bring any change in chemical composition of a substance are known as physical properties.

For example, shape, size, mass, volume, density, etc of a substance are all physical properties.

And, a property that changes chemical composition of a substance is known as chemical property.

For example, precipitation, reactivity, toxicity etc are chemical property.

Therefore, ability to react with acid is a chemical property.

2).   It is known that physical changes are reversible in nature because no change in chemical composition takes place in such changes.

Whereas chemical changes are irreversible in nature because they cause change in chemical composition of the substance.

So, when substance B returns to its original color then it means the change is reversible. Hence, substance B has undergone a physical change.

On the other hand, substance A does not return to its original color. Therefore, it means chemical change has occurred in substance A.

Hence, the statement a chemical change occurred in substance A, and a physical change occurred in substance B, is true.

3).  Since, it is known that 1 pound equals 453.592 g. Therefore, we will convert 2.5 pound into grams as follows.

                    $2.5 pound \times \frac{453.592 g}{1 pound}$  

                        = 1133.98 g

or,                     = $1.13 \times 10^{3}$ g

Thus, in 2.5 pound sample there are $1.13 \times 10^{3}$ g.