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SSC CGL 2021 PYQ — Question 42

SSC CGL - 23 Aug 2021 - Shift 3 • General Awareness • Q42

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In the following passage, some words have been deleted. Fill in the blanks with the help of the alternatives given. Select the most appropriate option for each blank.
Essaouira's origins stretch back to prehistoric times, and this spot on Morocco's Atlantic
coast (1)______ a centre of culture and commerce ever since. (2)______ centuries, the harbour town was an important trading post (3)______ both a seaport and as the north-western terminus of a caravan (4)______ stretching across the desert to Timbuktu (5)______ Africa’s interior.

How many oxygen atoms are present in a molecule of potassium permanganate?

Show answer & explanation

Correct answer: B

Explanation

The correct answer is option 2 i.e. Four

  • Potassium permanganate is prepared by fusion of MnO2 with an alkali metal hydroxide and an oxidising agent like KNO3 . This produces the dark green K2MnO4 which disproportionates in a neutral or acidic solution to give permanganate KMnO4.
  • Potassium permanganate forms dark purple (almost black) crystals which are isostructural with those of KClO4 . The salt is not very soluble in water (6.4 g/100 g of water at 293 K), but when heated it decomposes at 513 K