Answer:

Explanation:
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In this case, when performing units conversions involving two proportional factors we need to make sure we first convert to the base unit and then to the target one; thus, since 1 kg = 1000 g and 1 g = 1000 mg, we set up the following expression:

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The number 4 in the 4/2He indicates the atomic mass number of helium.
Answer: Option 3
<u>Explanation:
</u>
The elements present in periodic table generally represented as
. Here X will be the element in the periodic table, A is the atomic mass number of the element X and Z is the atomic number of the element X.
So, the number 4 is the atomic mass number of He and He-4 is the stable isotope of helium which can also be termed as alpha particle.
Mass number = number of protons + neutrons count.
Thus the number 4 denotes the Helium's atomic mass number.
<u>Answer:</u> The volume of stock solution needed is 0.016 L
<u>Explanation:</u>
To calculate the volume of stock solution, we use the equation:

where,
are the molarity and volume of the stock solution
are the molarity and volume of diluted solution
We are given:

Putting values in above equation, we get:

Hence, the volume of stock solution needed is 0.016 L