Which of the following is the correct ascending order of the given minerals in terms of their presence in the Earth's crust? 1. Amphibolite; 2. Mica; 3. Pyroxene.
- (a)2, 3, 1
- (b)1, 2, 3
- (c)2, 1, 3
- (d)1, 3, 2
Correct — C, the order 2, 1, 3 (mica, then amphibolite/amphibole, then pyroxene). The robust part is that pyroxene, at roughly 11 percent of the crust, is clearly the most abundant of the three, so it must come last in an ascending order. Between amphibole and mica, standard figures sit near 5 percent each and vary by source; this option places mica below amphibole. That ordering is genuinely disputed — option (b), 1, 2, 3 (amphibole below mica), is nearly as defensible, and only the pyroxene-last part can be stated with confidence.
- (a)2, 3, 1 — This puts amphibolite last, implying it is the most abundant of the three. Pyroxene (about 11 percent of the crust) is the most abundant and must come last, so ending on amphibolite is wrong.
- (b)1, 2, 3 — This is the main rival, not a clear error: it agrees pyroxene is last but orders amphibole below mica. Because amphibole and mica are near-tied in crustal share, it is rejected here only because the store reads mica as the least abundant of the two.
- (d)1, 3, 2 — This puts mica last, implying mica is the most abundant. Pyroxene is more abundant than mica, so pyroxene, not mica, must occupy the final position.
Amphiboles, micas and pyroxenes are all rock-forming silicate mineral groups in the Earth's crust. Feldspars dominate the crust (about half), while these three each make up a smaller share. Pyroxenes are notably more abundant than either amphiboles or micas, which sit close together near a few percent each.
The safe anchor is that pyroxene is the most abundant of the three, so in ascending order it comes last; that alone eliminates the options ending in amphibolite or mica. The amphibole-versus-mica ranking is close and source-dependent, which is why this item is best treated as disputed rather than clear-cut.
- Amphibole, mica and pyroxene are rock-forming silicate mineral groups.
- Pyroxene is the most abundant of the three (roughly 11 percent of the crust), so it ranks last in ascending order.
- Amphibole and mica are close in abundance (around 5 percent each), so their relative order is source-dependent.
- Feldspar, not any of these three, is the single most abundant mineral group, about half the crust.
- Assuming any of these is more abundant than feldspar (it is not).
- Placing mica or amphibole last instead of pyroxene.
- Treating the near-tied amphibole/mica order as settled.
NDA/UPSC ask to rank crustal minerals or name the most/least abundant — anchor on feldspar (about half) and remember pyroxene outranks mica and amphibole.
Which one of the following is present in the largest amount in terms of per cent by mass in the earth's crust?
- (a) Silicon
- (b) Oxygen
- (c) Carbon
- (d) Calcium
Answer(b) Oxygen
The crustal-abundance theme at the element level. Oxygen (about 46 percent) and silicon dominate the crust by mass, the same 'what makes up the crust' knowledge this NDA question tests at the mineral level.
Consider the following statements with reference to Feldspar mineral : 1. Half of the earth's crust is composed of feldspar 2. It has light cream to salmon pink colour 3. Magnesium is a common element in all types of feldspar Which of the statements given above is/are correct?
- (a) 1 only
- (b) 1 and 2 only
- (c) 2 and 3 only
- (d) 1, 2 and 3
Answer(b) 1 and 2 only
Same crustal-abundance ground. It fixes feldspar as roughly half the crust — the benchmark against which amphibole, mica and pyroxene (each a few percent) are ranked in this NDA-I question.
Which one of the following is correct?
- (a) Pyroxene is commonly found in meteorites
- (b) Amphiboles form about 20% of the Earth’s crust
- (c) Quartz is soluble in water
- (d) The word ‘sedimentary’ is derived from the Latin word kelimentum
Answer(a) Pyroxene is commonly found in meteorites
The same silicate minerals, including pyroxene and amphibole. That item also flags that amphiboles are not about 20 percent of the crust, matching the modest few-percent shares that let pyroxene outrank them here.
- practice — not a real PYQ
Which single mineral group makes up about half of the Earth's crust?
- (a)Quartz
- (b)Feldspar
- (c)Mica
- (d)Pyroxene
Answer(b) Feldspar — feldspars form roughly half the Earth's crust, more than any other mineral group.
- practice — not a real PYQ
Among amphibole, mica and pyroxene, which is the most abundant in the Earth's crust?
- (a)Amphibole
- (b)Mica
- (c)Pyroxene
- (d)All are equal
Answer(c) Pyroxene — pyroxene (about 11 percent) is the most abundant of the three silicate groups.