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2 years ago

Please help me! Physical change involves a change in composition. True or False

Chemistry

1 answer:

Brums [2.3K]2 years ago

3 0

Answer:

FALSE!!

Explanation:

Physical changes occur when objects or substances undergo a change that does NOT change their chemical composition. This contrasts with the concept of chemical change in which the composition of a substance changes or one or more substances combines or break up to form new substances.

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I need help with this question please someone tell me the answer for this

Andrej [43]

Aueyeowosy yo this is my answer

5 0

2 years ago

An inverted pyramid is being filled with water at a constant rate of 45 cubic centimeters per second. The pyramid, at the top, h

vaieri [72.5K]

Answer:

13.20 cm/s is the rate at which the water level is rising when the water level is 4 cm.

Explanation:

Length of the base = l

Width of the base = w

Height of the pyramid = h

Volume of the pyramid = $V=\frac{1}{3}lwh$

We have:

Rate at which water is filled in cube = $\frac{dV}{dt}= 45 cm^3/s$

Square based pyramid:

l = 6 cm, w = 6 cm, h = 13 cm

Volume of the square based pyramid = V

$V=\frac{1}{3}\times l^2\times h$

$\frac{l}{h}=\frac{6}{13}$

$l=\frac{6h}{13}$

$V=\frac{1}{3}\times (\frac{6h}{13})^2\times h$

$V=\frac{12}{169}h^3$

Differentiating V with respect to dt:

$\frac{dV}{dt}=\frac{d(\frac{12}{169}h^3)}{dt}$

$\frac{dV}{dt}=3\times \frac{12}{169}h^2\times \frac{dh}{dt}$

$45 cm^3/s=3\times \frac{12}{169}h^2\times \frac{dh}{dt}$

$\frac{dh}{dt}=\frac{45 cm^3/s\times 169}{3\times 12\times h^2}$

Putting, h = 4 cm

$\frac{dh}{dt}=\frac{45 cm^3/s\times 169}{3\times 12\times (4 cm)^2}$

$=13.20 cm/s$

13.20 cm/s is the rate at which the water level is rising when the water level is 4 cm.

3 0

3 years ago

The movement of the liquid in a thermometer shows changes in temperature. An increase in temperature indicates the molecules in

olya-2409 [2.1K]

Answer:

2: Moved faster and spread farther apart.

Explanation:

Restate the question: The movement of the liquid in a thermometer shows changes in temperature. An increase in temperature indicates the molecules in the liquid.

1. moved slower and closer together.

2.moved faster and spread farther apart.

3. contracted in size when heated.

4. expanded in size when heated.

Water that is cold does not have the energy to bounce of the walls, instead it is like a group of animals they group together for the warmth of the others when it gets really cold.

So it cant be 1.

We all know that power lines sag lower on a hot day (or a tire for a car, it has increases pressure). but those are different types of molecules.

So that rules out 3 and 4.

Which leaves you with 2.

The increase in temperature causes the water molecule to gain energy and move quickly, which resulted in water molecule that are farther apart and an increase in water volume.

Hope it helps!

7 0

2 years ago

Read 2 more answers

Which of the following will have the lowest boiling point?

mash [69]

Answer: C

Explanation:

3 0

3 years ago

Read 2 more answers

A container of oxygen with a volume of 60 L is heated from 300 K to 400 k, What is the new volume?

Lunna [17]

Answer:

80L

Explanation:

V1/T1 = V2/T2

V2 = V1 T2/T1

T1 = 300K

V1 = 60L

T2 = 400K

V2 = ?

V2 = V1 T2/T1

V2 = (60L)(400K) / (300K)

V2 = 80L

7 0

2 years ago