ILL GIVE BRAINLIST............ have to answer all!!!!

Chemistry

1 answer:

7nadin3 [17]3 years ago

6 0

1 is seconds and meters m/s

2 is seconds and meters m/s^2

3 Newton kg/m

4 Kilograms

Hope this helps!

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Which of the following measurements is used to measure the enthalpy of combustion? A. None of these B. Measuring the change in t

DaniilM [7]

Answer: Option (C) is the correct answer.

Explanation:

In a substance, the total energy of its molecular motion is known as heat. Whereas when we measure the average energy of molecular motion of a substance then it is known as temperature.

So, any increase or decrease in temperature will lead to change in heat of a substance.

When one mole of a substance is burned then the amount of energy released in the form of heat is known as heat of combustion.

Relation between heat and temperature is as follows.

q = $m \times C \times \Delta T$

Thus, we can conclude that to measure the enthalpy of combustion it cannot be measured, only calculated using the equation; q = $mc \Delta T$ .

4 0

3 years ago

The half-life of cesium-137 is 30 years. suppose we have a 200-mg sample.

Assoli18 [71]

a) To find the mass after t years:

we will use this formula:

A = Ao / 2^n

when A =the amount remaining

and Ao = the initial amount

and n = t / t(1/2)

by substitution:

∴ A = 200 mg/ 2^(t/30y)

b) Mass after 90 y :

by using the previous formula and substitute t by 90 y

A = 200mg/ 2^(90y/30y)

∴ A = 25 mg

C) Time for 1 mg remaining:

when A= Ao/ 2^(t/t(1/2)

so, by substitution:

1 mg = 200 mg / 2^(t/30y)

∴2^(t/30y) = 200 mg by solving for t

∴ t = 229 y