Explanation:
Significant figure is the measure of how accurately something can be measured. It carries meaning contributing to its measurement resolution. It is important to use proper number of significant figures to get a precise measurement. For example, if we use a meter stick then measurements like 0.874 meters, or 0.900 meters, are good because they indicate that we can measure to the nearest millimeter. Whereas a measurement like 0.8 does not tell that a meter stick can measure to the nearest millimeter.
Answer:

Explanation:
Hello!
In this case, as we know the mass of the total sample, we can first compute the mass of oxygen:

Next, we compute the moles of each element:

Now, we divide the moles by 0.184 moles, the fewest ones, to obtain:

Therefore, the empirical formula is:

Regards!
Answer:
NH4Cl > Li2SO4 > CoCl3
Explanation:
Let us recall that the freezing point depression depends on the molality of the solution and the number of particles present.
Let us also recall that freezing point depression is a colligative property. It depends on the number of particles present in solution.
Usually, the more the number of particles present, the lower the freezing point. Hence, NH4Cl which has only two particles will have the highest freezing point while CoCl3 which has four particles will have the lowest freezing point.
Answer:
2 and 3
Explanation:
An element belongs to group 4 and period 3.