Which quantity can vary among atoms of the same element?

1 answer:

7 0

There is this thing called isotopes
it means that atoms of the same element can have a different number of neutrons.
if there is a change in the no. of neutrons, there will definitely be a change in the mass number.

so the answer is A) mass number

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When CO2(g) reacts with H2(g) to form C2H2(g) and H2O(g), 23.3 kJ of energy are absorbed for each mole of CO2(g) that reacts. Wr

kupik [55]

Answer:

$2CO_{2}(g)+5H_{2}(g)\rightarrow C_{2}H_{2}(g)+4H_{2}O(g)-46.6kJ$

Explanation:

As energy is absorbed therefore it is an endothermic reaction. Hence energy value should be written in the product side with a negative sign.

Reaction: $CO_{2}(g)+H_{2}(g)\rightarrow C_{2}H_{2}(g)+H_{2}O(g)$

C balance: $2CO_{2}(g)+H_{2}(g)\rightarrow C_{2}H_{2}(g)+H_{2}O(g)$

H and O balance: $2CO_{2}(g)+5H_{2}(g)\rightarrow C_{2}H_{2}(g)+4H_{2}O(g)$

Here 2 moles of $CO_{2}$ react. So, energy absorbed during the reaction is $(2\times 23.3)$ kJ or 46.6 kJ

Energy balance: $2CO_{2}(g)+5H_{2}(g)\rightarrow C_{2}H_{2}(g)+4H_{2}O(g)-46.6kJ$

Balanced thermochemical equation:

$2CO_{2}(g)+5H_{2}(g)\rightarrow C_{2}H_{2}(g)+4H_{2}O(g)-46.6kJ$

3 0

2 years ago

There is water on the pan of the scale as you measure the mass of an object. If you were to ignore the water, what would be the

mihalych1998 [28]

Remember that density refers to the "mass per unit volume" of an object.

So, if an object had a mass of 100 grams and a volume of 100 milliliters, the density would be 100 grams / 100 ml.

In the question, water on the surface of the scale would add weight, so the mass of the object that you're weighing would appear to be heavier than it really is. If that happens, you'll incorrectly assume that the density is GREATER than it really is

As an example, suppose that there was 5 ml of water on the surface of the scale. Water has a density of 1 gram per milliliter (1 g/ml) so the water would add 5 grams to the object's weight. If we use the example above, the mass of the object would seem to be 105 grams, rather than 100 grams. So, you would calculate:

density = mass / volume
density = 105 grams / 100 ml
density = 1.05 g/ml

The effect on density would be that it would erroneously appear to be greater

Hope this helps!

Good luck

6 0

2 years ago

In fractional distillation, liquid can be seen running from the bottom of the distillation column back into the distilling flask

shepuryov [24]

Answer:

substances with a higher boiling point are returning back to the flask which allows another substances with the specific context temperature (lower boiling point) to boil over and be purified.

Explanation:

The reason it happens because the lower boiling point substance vaporizes and crosses over while the other substance is waiting for its boiling point to reach

7 0

2 years ago

Uranium–232 has a half–life of 68.9 years. A sample from 206.7 years ago contains 1.40 g of uranium–232. How much uranium was or

givi [52]

<u>Answer:</u> The initial amount of Uranium-232 present is 11.3 grams.

<u>Explanation:</u>

All the radioactive reactions follows first order kinetics.

The equation used to calculate half life for first order kinetics:

$t_{1/2}=\frac{0.693}{k}$