Answer : The smallest unit of a substance that behaves like the substance is, molecule.
Explanation :
Pure substance : It is defined as a substance that is made by the combination of only one type of atom or only one type of molecule.
Compound : It is a pure substance which is made from atoms of different elements combined together in a fixed ratio by mass.
Element : It is a pure substance which is composed of atoms of similar elements.
Molecule : It is the smallest particle in the chemical compound or chemical element or a substance that has the same chemical properties of that compound or element.
Hence, the smallest unit of a substance that behaves like the substance is, molecule.
<u>Answer:</u> The correct option is
<u>Explanation:</u>
A catalyst is defined as the chemical species that increases the reaction rate but does not participate in it and is left behind after the completion.
A homogeneous catalyst is one that is present in the same phase as the reactants and products.
A heterogeneous catalyst is one that is present in different phase as that of reactants and products.
For the given chemical reaction:

As all the reactants and products are in gaseous state so, the homogeneous catalyst must also be in the gaseous state only.
Hence, the correct option is 
Answer: -
Solubility of a substance depend on the balance of intermolecular forces between the solvent and solute, and the entropy change that accompanies this process.
Temperature and pressure also plays a role in solubility.
A solution having Group 1 cations like lithium, sodium, potassium etc are always soluble.
A solution having NH₄⁺ is soluble.
All salts with anion as nitrates, acetates, chlorates, and perchlorates are soluble in water.
Answer:
The length of an edge of this unit cell is 407.294 pm
Explanation:
Face centered cubic structure contains 4 atoms in each unit cell and 12 coordination number, occupying about 74% volume of the total cell. Face centered cubic structure is known for efficient use of space for atom packing.
To determine the edge length, a relationship between the radius of the atom and edge length is used.
X = R√8
Where;
X is the length of an edge of this unit cell
R is the radius of the gold atom = 144 pm = 144 X 10⁻¹² m
X = 144 X 10⁻¹²√8
X = 407.294 X 10⁻¹² m
X = 407.294 pm
Therefore, the length of an edge of this unit cell is 407.294 pm
Answer:
The mass percent of copper as element is the same.
Explanation:
First of all we need the reaction that is presented below:
→ 
The mass percent of copper (Cu) as element is the same because of during the reaction the element only transform its nature from copper carbonate (
) to copper oxide (
), the latter is a solid and will remain in the system.
On the other hand, you will note that the global percentage mass will be small because of the reaction produce (
) that is a gas and this one will escape for the system.
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