Answer = B = Neutrons and Mass Number
Isotopes are defined as those atoms which have same atomic number but different atomic masses.
Atomic mass is basically the number of protons and neutrons present in an atom.
Atomic number is the number of protons present in an atom.
So, in isotopes the number of protons are same but the number of neutrons vary due to which atomic masses also vary.
In given three isotopes, all have same number of protons but different number of neutrons.
i.e.
H-1 = 1 P + 0 N = 1 u (Proton)
H-2 = 1 P + 1 N = 2 u (Deuterium)
H-3 = 1 P + 2 N = 3 u (Tritium)
Hence, it is clear that the number after H shows a change in number of neutrons and mass number.
Answer: 
Explanation:Bond energy of H-H is 436.4 kJ/mole
Bond energy of C-H is 414 kJ/mol
Bond energy of C=C is 620 kJ/mol
Bond energy of C≡C is 835 kJ/mol
= {1B.E(C≡C)+2B.E(C-H) +1B.E(H-H)} - {1B.E(C=C)+4B.E(C-H)}
Double replacement :
2Na₃PO₄+3CaCl₂⇒6NaCl + Ca₃(PO₄)₂
<h3>Further explanation</h3>
1. A single replacement reaction is a chemical reaction in which one element replaces the other elements of a compound to produce new elements and compounds
2. Double-Replacement reactions. Happens if there is an ion exchange between two ion compounds in the reactant to form two new ion compounds in the product
3. Combination/syntesis : 2 or more reactants combine to form a new compound
4. Decomposition : the reactant is decomposed into 2/more products
If we look at the reaction options available, all of them can be included in the double replacement reaction, but we only choose the reaction from Sodium phosphate and Calcium chloride which leads to options: C because it is balanced (from the number of atoms in the same reactant and product) and is in accordance with the chemical formula of each compound (both products and reactants)
Answer:
Number of moles = 0.94 mol
Explanation:
Given data:
Number of moles of sodium chloride = ?
Volume of sodium chloride = 1.25 L
Concentration of solution = 0.750 mol/L
Solution:
Formula:
Concentration = number of moles/ volume in L
By putting values.
0.750 mol/L = number of mole / 1.25 L
Number of moles = 0.750 mol/L×1.25 L
Number of moles = 0.94 mol
