Answer:
The answer to your question is the third choice.
Explanation:
CaCO₃ ⇒ CaO + CO₂
Check if the reaction is balanced or unbalanced
Reactants Elements Products
1 Calcium 1
1 Carbon 1
3 Oxygen 3
As the number of atoms in the reactant is the same that the number of atoms in the products we conclude that the reaction is balanced.
So the correct answer is balanced because the total number of oxygen atoms is 3.
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Answer:
Visible light spectrum is a part of electromagnetic waves. The colors of the visible light spectrum are organised on the basis of their wavelength and frequency.
As the light or color having high frequency will have the shorter wavelength and vice versa, so colors in visible light spectrum arranged from highest frequency to lowest frequency or from shortest wavelength to highest wavelength. For example: The highest frequency color is violet and lowest frequency of visible light is red.
Answer: -
1.71 cm
Explanation: -
Density of aluminium = 2.70 g / 
Mass of aluminium = 13.5 g
We know density of a substance is the mass of the substance per unit volume.
Density = Mass / volume
Volume = Mass / density
Volume of aluminium = Mass of aluminium / Density of Aluminium
= 13.5 g / 2.70 g/
= 5
We know for a cube volume = 
Length of the cube = 
= 
=1.71 cm
Thus if the density of aluminium is 2.70g/
and the cube of aluminum weights 13.5 grams, 1.71 cm is the length of the edge of the cube
Answer:
0.66 × 10⁴² mol
Explanation:
Given data:
Moles of water = ?
Number of molecules of water = 3.99× 10⁶⁵ molecules
Solution:
The given problem will solve by using Avogadro number.
It is the number of atoms , ions and molecules in one gram atom of element, one gram molecules of compound and one gram ions of a substance.
The number 6.022 × 10²³ is called Avogadro number.
For example,
1 mole = 6.022 × 10²³ molecules of water
3.99× 10⁶⁵ molecules × 1 mol / 6.022 × 10²³ molecules
0.66 × 10⁴² mol
