The next three (03) items have two premises and two conclusions. If the premises are assumed to be true (irrespective of factuality), then, in respect of each of the items given below, which of the following conclusions follow logically ?
Premises: All metals are grey in colour. Some metals are heavy.
Conclusions:
- I. All heavy metals are grey in colour.
- II. All light metals are not grey in colour.
Only I
Only II
Both I and II
Neither I nor II
Answer is Wrong!
Answer is Right!
This question was previously asked in
UPSC CAPF – 2015
Premise 2: Some metals are heavy. (Some M are H)
Conclusion I: All heavy metals are grey in colour.
“Heavy metals” refers to the set of things that are both heavy and metal (H ∩ M). According to Premise 1, anything that is a metal is grey (M ⊆ G). Therefore, if something is a heavy metal, it must first be a metal, and thus it must be grey. So, H ∩ M ⊆ G. Conclusion I logically follows.
Conclusion II: All light metals are not grey in colour.
“Light metals” refers to the set of things that are metals but not heavy (M ∩ not-H). According to Premise 1, all metals are grey (M ⊆ G). This means *any* metal, regardless of whether it is heavy or light, must be grey. Therefore, light metals are grey. Conclusion II, stating that light metals are *not* grey, contradicts Premise 1 and is false.