Answer is: 4) The same subscripts are on each side of the equation.
For example, balanced chemical reaction:
2Mg + O₂ → 2MgO.
1) The same number of atoms is on each side of the equation: two magnesium atoms and two oxgen atoms.
2) The formulas for all substances are correct: in magnesium oxide (MgO), magnesium has oxidation number +2 and oxygen -2, so formula is good, because compound must be neutral.
3) The same mass is represented on each side of the equation: because there is same number of atoms, the mass is the same.
4) The same subscripts are on each side of the equation: oxygen does not have same subscripts.
Answer:
The enthalpy for given reaction is 232 kilo Joules.
Explanation:
...[1]
..[2]
..[3]
..[4]
2 × [2] + [3] - [1] ( Using Hess's law)



The enthalpy for given reaction is 232 kilo Joules.
When fossil fuels are burnt, CO2 is released into the air and is taken up by plants during photosynthesis to form glucose and subsequently starch.
Fossil fuels contain a large proportion of carbon atoms. When fossil fuels are burnt, these carbon atoms are released as carbon dioxide and escape to the atmosphere as atmospheric CO2 in air.
Recall that plants take up the CO2 in air during the process of photosynthesis. This CO2 becomes combined with water in the presence of sunlight to form glucose.
This glucose is converted to starch and stored in plant tissues. This is how the carbon atom inside a fossil fuel becomes a carbon atom inside a plant.
Learn more: brainly.com/question/1388366
Answer:
Substance is Aluminium
Explanation:
We are given;
Mass; m = 13.5 grams
Volume; V = 5 cm³
Formula for density is;
density = m/V
Density = 13.5/5
Density = 2.7 g/cm³
From the table attached, we can see that the element with a corresponding density of 2.7 is Aluminium
The answer should be A, the number of electrons increases by 1, from left to right.
Across the periods (horizontal direction) in periodic table, each element has one more electron then the one before it. The number of period determines the number of occupied electron shells of the elements in that period. Which means, period 1 elements have 1 occupied electron shell, period 2 has 2, period 3 has 3 etc.
Therefore, the answer is A, we always go from left to right, and plus since period 2 elements only have 2 occupied electrons so their 2nd electron shell electrons must increase throughout the period.