Q611. Identify the only non-metal that exists as a liquid at room temperature.
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Q612. Consider the following statements about the reactivity series of metals:
I. Metals at the top of the series can displace metals below them from their salt solutions.
II. Gold and platinum are placed at the bottom of the series.
III. Metals below hydrogen in the series can easily liberate hydrogen gas from dilute acids.
Which of the above statement(s) is/are correct?
I. Metals at the top of the series can displace metals below them from their salt solutions.
II. Gold and platinum are placed at the bottom of the series.
III. Metals below hydrogen in the series can easily liberate hydrogen gas from dilute acids.
Which of the above statement(s) is/are correct?
Explanation
In the reactivity series, more reactive metals can displace less reactive ones from their compounds. Highly unreactive metals like gold and platinum are found at the bottom. However, only metals placed above hydrogen in the series are capable of displacing hydrogen from dilute acids to release gas. Metals below hydrogen, such as copper and silver, do not react in this way.
Q613. Metal oxides that exhibit both acidic and basic behaviors are known as:
Explanation
Amphoteric oxides are metallic oxides that show both acidic and basic characteristics. They can react with both acids and bases to produce salt and water. Common examples include aluminum oxide and zinc oxide. This dual reactivity is important in chemistry for identifying specific metal ions and is utilized in industrial processes where pH control and chemical neutralization are necessary for various reactions.
Q614. The process of heating carbonate ores strongly in limited air to convert them into oxides is termed:
Explanation
Calcination is a metallurgical process where carbonate ores are heated strongly in the absence or limited supply of air. This thermal treatment causes the ore to decompose, releasing carbon dioxide gas and leaving behind the metal oxide. This step is essential for preparing the ore for the subsequent reduction process, which eventually extracts the pure metal from its naturally occurring form.
Q615. Anodizing is a process of forming a thick oxide layer to prevent corrosion on which of the following metals?
Explanation
Anodizing is an electrochemical process used to increase the thickness of the natural oxide layer on the surface of aluminum parts. This thick, protective coating improves corrosion resistance, increases surface hardness, and allows for the application of dyes for decorative purposes. Unlike iron, which rusts when oxidized, the aluminum oxide layer is stable and adheres strongly to the metal, protecting it further.
Q616. Galvanization is a method of protecting steel and iron from rusting by coating them with a thin layer of:
Explanation
Galvanization is a widely used method for protecting iron and steel from atmospheric corrosion or rusting. It involves applying a thin, protective coating of zinc over the metal surface. Zinc acts as a sacrificial barrier; even if the coating is scratched, the zinc will corrode in preference to the underlying iron, effectively extending the lifespan of structural components and various hardware.
Q617. The most abundant metal in the Earth’s crust by weight is:
Explanation
Aluminum is the most abundant metallic element found in the Earth’s crust, making up approximately eight percent of its total weight. While it is extremely common, it is never found in its pure metallic form in nature; instead, it occurs in various minerals, most notably bauxite. Due to its abundance, lightweight, and corrosion resistance, it is a critical material for modern industry.
Q618. Arrange the following metals in decreasing order of their chemical reactivity:
I. Calcium
II. Potassium
III. Magnesium
IV. Sodium
Which of the following is the correct order?
I. Calcium
II. Potassium
III. Magnesium
IV. Sodium
Which of the following is the correct order?
Explanation
The reactivity of metals determines how easily they lose electrons to form positive ions. Potassium is the most reactive of the group, followed by sodium and then calcium. Magnesium is the least reactive among these four. Therefore, the correct sequence in decreasing order of their chemical reactivity is potassium, then sodium, followed by calcium, and finally magnesium at the end.
Q619. Who is credited with the first discovery and naming of the "cell" in 1665?
Explanation
Robert Hooke was an English scientist who, in 1665, observed thin slices of cork under a primitive compound microscope. He noticed thousands of tiny, empty compartments that reminded him of the small rooms, or "cells," inhabited by monks. While he was actually looking at dead plant cell walls, his use of the term laid the foundation for the field of modern biology.
Q620. Which of the following is not a postulate of the classical Cell Theory?
Explanation
Classical cell theory says that all organisms are made of cells, the cell is the basic unit of life and all cells come from pre-existing cells. It does not say that all cells have a true nucleus, since bacterial cells have none, so D is not a postulate.Answer key for these questions
| Q | Correct answer |
|---|---|
| 611 | (c) Bromine |
| 612 | (a) I and II only |
| 613 | (d) Amphoteric oxides |
| 614 | (a) Calcination |
| 615 | (c) Aluminum |
| 616 | (a) Zinc |
| 617 | (d) Aluminum |
| 618 | (a) II, IV, I, III |
| 619 | (c) Robert Hooke |
| 620 | (d) All cells contain a true nucleus and membrane-bound organelles |
Frequently asked questions
How many RAS Prelims practice MCQs are there on RAS Prelims?
This page has 9654 practice MCQs on the RAS Prelims syllabus. Each has the correct answer, and most have an explanation.
How should I practise MCQs for RAS Prelims?
Attempt each question first, then open the answer and read the explanation. Practise one chapter at a time, note the facts you got wrong and revise them. Repeat the chapter after a few days.
Are these actual RAS Prelims past-paper questions?
No. These are practice questions written for the RAS Prelims syllabus. They follow the pattern the exam uses: factual questions, statement-based questions, match-the-list and assertion-reason.