Answer : The correct option is, (B)
Explanation :
Balance equation : Balanced equation are those equation in which the number of atoms of each element and the total charge must be same on products side and reactants side.
In the given options, only option (B) equation has correct formula and also a balanced equation.

while the other options has incorrect formulas and also an unbalanced equations.
The correct equation for option A is, 
The correct equation for option C is, 
The correct equation for option D is, 
Hence, the correct answer is, (B) 
Answer:
2x1000 = 2000
Explanation:
10^3 = 10×10×10 = 1000
exponent , the ^3 means multiply the number by itself 3 times, if it was ^4, it would be 4 times and so forth.
another trick for 10s is just put the 1 and the exponents number of 0's after the 1. so in this case, put three 0's: 1,000
Answer:
A mixture of 100. mL of 0.1 M HC3H5O3 and 50. mL of NaOH
Explanation:
The pH of a buffer solution is calculated using following relation

Thus the pH of buffer solution will be near to the pKa of the acid used in making the buffer solution.
The pKa value of HC₃H₅O₃ acid is more closer to required pH = 4 than CH₃NH₃⁺ acid.
pKa = -log [Ka]
For HC₃H₅O₃
pKa = 3.1
For CH₃NH₃⁺
pKa = 10.64
pKb = 14-10.64 = 3.36 [Thus the pKb of this acid is also near to required pH value)
A mixture of 100. mL of 0.1 M HC3H5O3 and 50. mL of NaOH
Half of the acid will get neutralized by the given base and thus will result in equal concentration of both the weak acid and the salt making the pH just equal to the pKa value.
Answer: I don't know if this helps you or not, but this is from study.com:
I'm so sorry if it doesn't:
Explanation: Iron(III) oxide reacts with carbon monoxide according to the balanced equation:
Fe₂O₃ + 3CO ➡️ 2Fe + 3CO₂
A reaction mixture initially contains 23.00g Fe₂O₃ and 15.40g CO.