<span>7.379 * 10^(-4) is measured, hence prone to error, either human error or via measuring device. In this case,
100 cm = 1 m is written in stone and is unquestionable.
The density of the gold is 19.3 g/cm^3 and could be an approximation.
The approximation is good to at least one night.</span>
Given :
A 10.99 g sample of NaBr contains 22.34% Na by mass.
To Find :
How many grams of sodium does a 9.77g sample of sodium bromine contain.
Solution :
By law of constant composition , in any given chemical compound, the elements always combine in the same proportion with each other.
Therefore , percentage of Na by mass in NaBr will be same for every amount .
Percentage of Na in 9.77 g NaBr is 22.34 % too .
Gram of Na = 
.
Hence , this is the required solution .
Answer:
Barium has a greater radius than magnesium
Explanation:
Barium and magnesium are two elements which belong to the same group, group 2A. This means that the two elements have two valence electrons in their outer shell.
The difference is, however, since barium is lower in group than magnesium, it has more electron shells than magnesium and, therefore, its radius is greater. The attraction force between the nucleus and the valence electrons in barium is lower as a result, as force is inversely proportional to distance. Hence, a lower amount of energy is required to remove the valence electrons from barium.
