Answer:
<em>The correct option is A) The atom has changed over the years.</em>
Explanation:
Option A is not correct because an atom does not change. It remains the same always. The structure of an atom will always contain neutrons, protons and electrons.
Scientific theories tend to change over time as new information is brought up. Novel techniques lead to more advanced experiments and results. As a result, a scientific theory is subjected to change whenever evidence is found for a new theory which challenges the older one.
The atomic theory has changed many times due to novel scientific techniques and experiments.
Magnesium oxide : MgO
Calcium bicarbonate: Ca(HCO3)2
aluminum carbonate: Al2(CO3)3 or C3Al2O9
Answer:
1. The metal atom/ion in these compounds are Ni and Ni2+ respectively.
2. The electrons from s oribital will jump to d orbital and so I expect CO to donate electron pairs in 4p and 4s orbitals and form sp3 hybridisation.
Answer: There are about 0.28 molecules in 43.9 g of carbon tetrachloride. If you are rounding up, it would be 0.3
Explanation:
<u>Answer:</u> The amount of heat released is 56 MJ.
<u>Explanation:</u>
To calculate the number of moles, we use the equation:
Given mass of 
= 12 kg = 12000 g (Conversion factor: 1 kg = 1000 g)
Molar mass of = 30 g/mol
Putting values in above equation, we get:
The chemical reaction for hydrogenation of ethene follows the equation:
By Stoichiometry of the reaction:
When 1 mole of ethane releases 140 kJ of heat.
So, 400 moles of ethane will release = 
of heat.
Converting this into Mega joules, using the conversion factor:
1 MJ = 1000 kJ
So, 
Hence, the amount of heat released is 56 MJ.
