<span>The mass number of an ion is calculated by adding the neutrons and electrons together. In this case 159+107=266. However, since this ion has a +1 charge, you must add 1 to the electrons. This would give a total mass of 267.</span>
Balance the equation: 2Na + S --> Na2S
Using the given amount of the reactants in the reaction, calculate the amount of the product:
45.3g Na x (1 mol/22.99 g)= 1.97 mol of Na
105f S x (1 mol/ 32.06g) = 3.28 mol of S
The limiting reactant would be Na:
<span>1.97 mol Na x (1 mol Na2S/ 2 mol Na) x (78.04g/mol) = 76.87g of Na2S produced</span>
Answer: 3.59
Explanation:
(2.06)(1.743)(1.00)
2.06 × 1.743 × 1.00
= 3.59058
Two of the multiplied digits are represented in 3 significant figures. Therefore, for correct representation, the result of the product should be written to three significant figures.
3.59058 to 3 significant figures:
First three digits = 3.59
Fourth digit '0' is less than 5, and thus rounded to 0 with other succeeding digits
Therefore, (2.06)(1.743)(1.00) to 3 significant figures equals :
3.59
Viruses are not classified as being alive in because of the fact that they can't reproduce.

An element is a substance that can't be broken down further. Lithium (Li) and calcium (Ca) are examples of elements.
Carbon monoxide (CO) and potassium bromide (KBr) are examples of compounds, which are made up of more than one element put together.