Answer: a. It receives a hydrogen ion.
Explanation: Base is a species which is capable of donating its negative quantity and accepting the positive one.
For example, ammonia is considered as a base because it is capable of donating its lone pairs of electrons and can accept an proton as well.
Here, out of the given options, Hydrogen 
is a proton which is acting as a positive species and hydroxide ion 
is a negative species.
Thus, option (A) is the correct answer as it will receive a hydrogen ion from another base making itself a conjugate acid.
Answer : The enthalpy change for the reaction is 1043 kJ/mol.
Explanation :
The given chemical reaction is:
As we know that:
The enthalpy change of reaction = E(bonds broken) - E(bonds formed)
![\Delta H=[(2\times B.E_{C\equiv O})+(1\times B.E_{O\equiv O})]-[2\times B.E_{C=O}]](https://tex.z-dn.net/?f=%5CDelta%20H%3D%5B%282%5Ctimes%20B.E_%7BC%5Cequiv%20O%7D%29%2B%281%5Ctimes%20B.E_%7BO%5Cequiv%20O%7D%29%5D-%5B2%5Ctimes%20B.E_%7BC%3DO%7D%5D)
Given:
= 1074 kJ/mol
= 499 kJ/mol
= 802 kJ/mol
Now put all the given values in the above expression, we get:
![\Delta H=[(2\times 1074kJ/mol)+(1\times 499kJ/mol)]-[2\times 802kJ/mol]](https://tex.z-dn.net/?f=%5CDelta%20H%3D%5B%282%5Ctimes%201074kJ%2Fmol%29%2B%281%5Ctimes%20499kJ%2Fmol%29%5D-%5B2%5Ctimes%20802kJ%2Fmol%5D)
Therefore, the enthalpy change for the reaction is 1043 kJ/mol.
Answer:
1.085 x 10²⁴
Explanation:
The answer is not in your choices, but it maybe due to a typo but to get the answer to this, you just need to convert the grams to moles, then moles to atoms.
First we get the mass of the molecule for every mole. Get the atomic mass of each element and multiply it by the number of atoms present then get their total.
N₂O₃
Element number of atoms Atomic mass TOTAL
N 2 x 14.007 28.014
O 3 x 15.999 <u>47.997</u>
76.011 g/mole
So now we know for every 1 mole of N₂O₃ there are 76.011 g of N₂O₃.
Next we need to see how many moles of N₂O₃ are there in 137.0g of N₂O₃.
Now we know that we have 1.802moles of N₂O₃.
We use Avogadro's constant to find out how many atoms there are. Avogadro's constant states that for every mole of any substance, there are 6.022140857 × 10²³ atoms.
Calcium carbonate will be formed which is insoluble in water.
The answer is a) K and CrO4 only.
