Answer:
By balancing the chemical equation
Explanation:
The Law of Conservation of Matter states that matter cannot be destroyed nor created.
That is, you must have the same amount of matter before and after a reaction.
Atoms are made of matter, so you must have the same number of each type of atom in the reactants as in the products. You must balance the equation.
Consider the reaction
2H₂ + O₂ ⟶ 2H₂O
You must have 2s in front of H₂ and H₂O to balance the atoms.
They give you four atoms of H and two atoms of O on each side of the arrow.
Answer:

Explanation:
1. Mass of zinc
The density of zinc is 7.14 g/cm³
D = m/V

2. Volume of aluminium
The density of aluminium is 2.60/cm³.

Answer:They are all controlled by the human beings.
Explanation:
The selective breeding, cloning and genetic engineering are some of the techniques which is induced by the human efforts.
In case of selective breeding the male and female species having the selective characters are mated with each other so that the offspring produced has the desired characters. It neither requires any enzyme nor uses udder cells.
In case of genetic engineering, the gene of interest is inserted in the bacterial species by the help of vector so that when the bacterial species amplify the gene of interest. This is how the desired products are produced by bacterial species. Example: Insulin production.
Cloning can be defined as another technique made by human beings in which the genetically identical species is made naturally or artificially for the benefit of the mankind.
Answer:
Here's what I get
Explanation:
1. Water
The O-H bond in water is highly polar.
It has about one-third ionic character.
The partially-positive H atoms and partially negative O atoms strongly attract each other by hydrogen bonds.
It takes a large amount of energy to separate the water molecules from each other.
Thus, the boiling point of water is relatively high (100 °C).
2. Acetone
The C=O bond in acetone is much less polar.
It is less than 20 % ionic.
The dipole-dipole attractions in acetone are much weaker than the hydrogen bonds in water.
It takes much less energy to separate the acetone molecules from each other.
Thus, even though the molar mass of acetone is more than three times that of water, the boiling point of acetone is only 56 °C.
Answer:
An exothermic combination reaction
Explanation:
There are two aspects to consider regarding this reaction, as it doesn't only provide the reaction but it also includes the enthalpy change for the reaction.
In terms of this reaction, magnesium atom combines with oxygen molecule to produce one product, magnesium oxide. This may be classified as a combination reaction.
Now, we also see that we released a total of 1199.66 kJ of heat as our product. There are two types of reactions in terms of the enthalpy change: exothermic reactions (those that release heat) and endothermic reactions (those that consume heat).
The enthalpy change for exothermic reactions is negative and it's positive for endothermic reactions.
However, here we're actually given heat as a product. If we have it as a product, this means heat was released into the surrounding by this reaction and we have an exothermic reaction.