The correct answer would be option 3. I order for a single displacement to occur there must be a single element and one compound. From then, the single element will then swap places with one of the elements in the compound (or in this case single circle and combined circles). Hope this helped!
b............................................
Answer:

Explanation:
Mole ratio


Moles of CO₂

Use formula to find mass

Relative molecular mass of CO₂ = 12 + 16 × 2 = 44


Answer:
Second Law
Explanation:
Newton's second law states that the acceleration caused in a body is directly proportional to the force applied and inversely proportion to the mass of the body.
This is given by :

In this case the suggestion given to reduce the aircraft's cargo load is the right move as reducing the load on the aircraft will decrease the mass of the whole aircraft. This in turn will help the aircraft to accelerate more as acceleration inversely varies with mass. Thus the aircraft will be able to reach its flying speed even on a short run way.
Hence, Newton's second law is applied.
Answer: (C) Statements (i) and (iii)
Explanation: According to byjus.com, group VII elements are known as Halogens.
Not only that, but bbc.co.uk says " Atoms of group 7 elements all have seven electrons in their outer shell. This means that the halogens all have similar chemical reactions ."
It may just be (b) though as these are chemical reactions.