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3 years ago

In terms of substances explain why evaporation of water is a physical change and not a chemical change

1 answer:

8 0

Physical change is changing physically it eg appearance while chemical change is the molecular bonds water is always defined as H2O and not change chemically. Hope this answers your question.

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A quantity of N2 occupies a volume of 1.4 L at 290 K and 1.0 atm. The gas expands to a volume of 3.3 L as the result of a change

lions [1.4K]

Answer:

$\rho = 0.50 g/L$

Explanation:

As we know that

PV = nRT

here we have

$P = 1.0 atm$

$P = 1.013 \times 10^5 Pa$

so we have

$V = 1.4 \times 10^{-3} m^3$

T = 290 K

now we have

$(1.013 \times 10^5)(1.4 \times 10^{-3}) = n(8.31)(290)$

$n = 0.06$

now the mass of gas is given as

$m = n M$

$m = (0.06)(28)$

$m = 1.65 g$

now density of gas when its volume is increased to 3.3 L

so we will have

$\rho = \frac{m}{V}$

$\rho = \frac{1.65 g}{3.3 L}$

$\rho = 0.50 g/L$

5 0

3 years ago

Imagine you are sitting on a sled and someone is about to push you down a hill. Which statement is accurate?

Dima020 [189]

The answer is:

Forces acting on the sled are paired with equal and opposite forces.

The explanation:

About to push you, this means that he doesn't push yet. If the sled is on level ground and no one is pushing it, then forces are equal and opposite.

The gravity force pulls down and the ground pushes up.

This is Newton's third law:

Newton's third law: If an object A exerts a force on object B, then object B must exert a force of equal magnitude and opposite direction back on object A.

This law represents a certain symmetry in nature: forces always occur in pairs, and one body cannot exert a force on another without experiencing a force itself.

We can also see Newton’s third law at work by taking a look at how people move about. Consider a swimmer pushing off from the side of a pool.

6 0

3 years ago

Read 2 more answers

Find the length of a microscope having magnifying power 100, if the focal lengths of the objective and eye piece are 2 cm and 5

sp2606 [1]

Answer:

L = 40 cm

Explanation:

A microscope is an optical instrument built by two lenses in such a way that the image of the first is formed within the distance of the other (eyepiece), so that the latter creates an enlarged virtual image of the object, for which the magnification of the microscope is the same to the multiplication of the magnification of each lens

M = - L / f₀ (25 cm / $f_{e}$ )