Answer:
20.11% of oxygen
Explanation:
The reaction is:
2CuO ⇒ 2Cu + O2
If you have an initial amoung of a sample, thi may be have impurities, so you have to start from products to know what you had at the begining.
to make a relation between reagents and products you need to change the mass to mol, then you can relate them with the molar ratio.
Now you have the initial amount of oxygen, to convert to percent you must divide the mass of oxygen between the mass of the sample and multiply by 100

The correct answer is - d. Carbon dioxide is an insignificant greenhouse gas.
To say that the carbon dioxide is an insignificant greenhouse gas is not a theory that is supporting the global warming, not to mention the fact that it is the total opposite.
The carbon dioxide (CO2) is actually the gas the contributes the most to the greenhouse effect. The reason for that is that the CO2 is a gas that has the property to trap the heat, thus the heat instead going back to the space, it is actually remaining in the atmosphere. That results in warmer temperatures on a global scale, as we can witness in the past century with the increasing amounts of CO2 into the atmosphere because of the human activities.
Q3.) acidic
q4.)that the solution is acidic
q5.)that the solution is alkaline