Chemistry Questions for NDA, CDS & CAPF: Quiz 2


Dear Aspirants, Chemistry is an important subject in various exams like NDA, CDS, AFCAT, CAPF and other Police Exams. Here at Defence Adda we provide you with the quizzes based on the syllabus and pattern of these exams. The questions asked are of 10+2 level and preparing with a wide variety of questions will help you ace in these exams. Here is a quiz based on the latest syllabus of these exams based on topics like Metals, Non-metals, Oxidation and Reduction, Periodic Table etc to help you prepare with a wide variety of questions. 

Q1. The pH of water at 25° c is 7. When it is heated at 100°C, the pH of water —
(a) Increases
(b) Decreases
(c) Remains same
(d) Decrease

Q2. An acid is a substance which —
(a) Donates a proton
(b) Accepts an electron
(c) Give H⁺ in water
(d) All

Q3. With reference to ionic compounds, consider the following statement: 
(a) Ionic compounds are insoluble in alcohol
(b) Ionic compounds in the solid state are good conductor of electricity
Which of these statements is/are correct?
(a) Only 1
(b) Only 2
(c) Both 1 and 2
(d) Neither 1 nor 2

Q4. Strongest bond is-
(a) C = C
(b) C = C 
(c) C ≡ C
(d) All are equally strong

Q5. The maximum number of hydrogen bonds in a H_2 O molecule is- 
(a) 1
(b) 2
(c) 3
(d) 4

Q6. Transition metals are often paramagnetic owing to- 
(a) High Melting point and Boiling Point
(b) The presence of vacant orbitals
(c) The presence of unpaired electrons
(d) Malleability and ductility

Q7.  Electron affinity of noble gases is - 
(a) Almost zero
(b) Low
(c) High
(d) Very high

Q8. All the elements in a group in the periodic table have the same- 
(a) Atomic weight
(b) Same number of valence electrons
(c) Atomic number
(d) None of these

Q9. “Which elements are arranged in increasing order of atomic weight, every eighth element has properties similar to the first”. This law had been given by- 
(a) Moseley
(b) Dobereiner
(c) Newland
(d) Lother-Mayer

Q10. Which of the following gases is heavier than oxygen?
(a) Carbon dioxide
(b) Ammonia
(c) Methane
(d) Helium

Q11. All isotopes of the same element have _________.
(a) Different atomic numbers and different atomic mass
(b) Different atomic numbers and the same atomic mass
(c) The same atomic number but different atomic masses
(d) The same atomic number and the atomic mass

Q12. What are the main components of Brass Alloy?
(a) Copper and Zinc
(b) Copper and Strontium
(c) Copper, Zinc and Nickel
(d) Copper and Nickel

Q13. Which of the following is a chemical formula of quicklime?
(a) Ca2O
(b) Ca2CO3
(c) CaO2
(d) CaO

Q14. The plants receive Nitrogen in form of: 
(a) Nitric oxide
(b) Nitrate
(c) Ammonia
(d) Nitride

Q15. What is formed when Magnesium is burnt?
(a) Baking Soda
(b) Calcium Carbonate
(c) Ash
(d) Vinegar



SOLUTIONS

S1. Ans. (b)
Sol. On heating, the extent of dissociation of water increase which leads to the increase in concentration of H+ ions as well as OH- ions. Hence, the PH of water decreases.

S2. Ans. (d)
Sol. Acids in solution have a pH below 7.0, a sour taste, releases hydroxyl ions in water, turn litmus paper red and accept an electron.

S3. Ans. (a)
Sol. Ions are charged particles, but ionic compounds can only conduct electricity if their ions are free to move. Ionic compounds do not conduct electricity when they are solid - only when dissolved in water or melted.

S4. Ans. (c)
Sol. A triple bond will always be found in a geometrically linear portion of the molecule. While a triple bond is the strongest type of bond, it is not three times stronger than a single bond because pi bonds are weaker than sigma bonds.

S5. Ans. (d)
Sol. In H2O molecule, oxygen has 2 hydrogen attached & 2 lone pair of electrons, so it has tendency to form 4 hydrogen bonds.

S6. Ans. (c)
Sol. Transition elements containing one or more unpaired electrons show paramagnetic behavior where the effects of individual electrons are not mutually compensated. The magnetic moment due to unpaired electron spins are aligned parallel to the external magnetic field more effectively.

S7. Ans. (a)
Sol. Large atoms have low ionization energy and low electron affinity. Therefore, they tend to lose electrons and do not tend to gain electrons. Any electrons added to a noble gas would have to be the first electron in a new (larger) energy level. This causes the noble gases to have essentially zero electron affinity.

S8. Ans. (b)
Sol. The elements in each group have the same number of electrons in the outer orbital. Those outer electrons are also called valence electrons. They are the electrons involved in chemical bonds with other elements.

S9. Ans. (c)
Sol. John Alexander Reina Newlands (26 November 1837 – 29 July 1898) was a British chemist. Newlands was the first person to devise a periodic table of chemical elements arranged in order of their relative atomic masses.

S10. Ans. (a)
Sol. For oxygen, a molecule consists of two oxygen atoms, and has a weight of 2 x 16 = 32. For carbon dioxide, there is one carbon atom (weight 12) and two oxygen atoms (mass 16 x 2) for a total of 44. This means that carbon dioxide should be about 44/32 = 1.375 times (ideally) as heavy as an equivalent volume of oxygen. In reality, carbon dioxide is 1.383 times as heavy as oxygen. Even after solidification carbon dioxide is slightly heavier than similar volume of solid oxygen.

S11. Ans. (c)
Sol. All isotopes of the same element have the same atomic number but different atomic masses.

S12. Ans. (a)
Sol. Brass is a metallic alloy that is made of copper and zinc. Brass is commonly used for decorative purposes primarily because of its resemblance to gold. It is also a commonly used to make musical instruments due to its high workability and durability.

S13. Ans. (d)
Sol. CaO is a chemical formula of quicklime

S14. Ans. (b)
Sol. Ammonium (NH4+) and nitrate (NO3-) are the predominant inorganic forms of nitrogen in the soil. Plants normally use nitrogen in the form of nitrate.

S15. Ans. (c)
Sol. When the magnesium metal burns it reacts with oxygen found in the air to form Magnesium Oxide. Oxygen and magnesium combine in a chemical reaction to form this compound. After it burns, it forms a white ash of the magnesium oxide.

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