From the chemical formula the total mass of the compound can be determined. The mass of the 1 mole of the compound is its molar mass. The atom by which the molecule is generated, the mass of these atoms are expressed in terms of amu or atomic unit mass, but after formation of a molecule in a particular ratio the mass of each of the atom becomes the total molecular weight of the generated molecule. In this case the molecule posses three atoms X, Y and Z which are in a ratio of 2:2:7. Thus the chemical formula of the compound can be written as 
.
So the total mass of the compound in amu is {(2×47)+(2×42)+(7×16)} = {94+84+112}=290 amu.
Thus 1 mole of the compound contains 290 amu or 290 g by mass.
Henceforth 20 gram of the compound is equivalent to (20/290) = 0.068 mole.
Answer:
There are approximately 5.55 moles
Explanation:
C) They each form similar compounds when combined with oxygen.
Explanation:
The given elements have a common characteristics as they each form similar compounds when combined with oxygen.
Beryllium, magnesium and calcium all are located in the alkaline earth group.
Elements in the same group have the same chemical properties.
- Density and melting point are physical properties of matter which varies down a group on the periodic table.
- Their reaction with oxygen denotes a statement of their chemical properties.
- Chemical properties of matter is a function of their valency.
- Group two elements have a valency of two. They have two electrons in their outermost shell.
- Therefore, they all form ionic bonds when they react with oxygen.
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Answer:15g
Explanation:
According to the law of conservation of mass, the mass of the products in a chemical reaction must equal the mass of the reactants.
10g + 5g ➡️ 15g
