Answer : The correct options are,
and 
Explanation :
Single displacement reaction : It is a type of chemical reaction in which the more reactive element displaces the less reactive element.
Option A reaction : 
It is an example of double displacement reaction because in this reaction a positive cation and a negative anion of the two reactants exchange their places to form two new products.
Option B reaction : 
It is an example of single displacement reaction.
Option C reaction : 
It is an example of combination reaction because in this reaction two reactants react to give a single product.
Option D reaction : 
It is an example of decomposition reaction because in this reaction a single reactant decomposes into two or more products.
Option E reaction : 
It is an example of single displacement reaction because in this reaction the most react element, aluminium displaces the less reactive element, hydrogen.
Hence, the options B and E are single displacement reactions.
Answer:
SO the awnser is 76.9 trust me
Explanation:
Answer:
option A = C₂H₄ + 3O₂ → 2CO₂ + 2H₂O
Explanation:
Law of conservation of mass:
This law stated that mass can not be created or destroyed in chemical reaction. It just changed from one to another form.
For example:
C₂H₄ + 3O₂ → 2CO₂ + 2H₂O
28 g + 96 g = 88 g + 36 g
124 g = 124 g
This reaction correctly hold the law of conservation of mass.
Other options:
C + 4H₂ → CH₄
12 g + 8g = 16 g
20 g = 16 g
This reaction do not hold the law of conservation of mass.
3H₂O → 3H₂ + 3O₂
54 g = 6 g + 96 g
54 g = 102 g
This reaction do not hold the law of conservation of mass.
2Na + Cl → NaCl
46 g + 35.5 g = 58.5 g
81.5 g = 58.5 g
This reaction do not hold the law of conservation of mass.
For any given element the mass number can be found by adding the protons and the neutrons.
In this case its 10 protons plus 11 neutrons which gives us 21 as the mass number.