MG SCHOOL EDUCATION: KREIS - SSLC Science Practice Examination

Question. 1

Ans: D

Solution:

Base: NaOH, KOH, NH4OH

Alcohol: C2H5OH

Question. 2

Ans: C. Basic

Solution:

So, to neutralize acidic mouth we have to take alkaline or basic toothpaste, which prevents damage to teeth by acidic environment. So, the correct answer is “C”.

Question. 3

Ans: C. Basic

Solution:

Crushed egg shell has composition CaCO3 reacts with acid and gives gas CO2 which turns lime water (Ca(OH)2) milky by producing CaCO3 again. The acid in given options is HCl.

CaCO3+2HCl→CaCl2+CO2+H2O

Ca(OH)2+CO2→CaCO3+H2O

Question. 4

Ans: D

Question. 5

Ans: B

Solution: The pH scale ranges from 0 to 14, with 7 being neutral. pHs less than 7 are acidic(H+) while pHs greater than 7 are basic(OH-).

Question. 6

Ans: B

Solution:

When citric acid is added to potassium permanganate solution, the purple solution loses its colour and becomes colourless.

Question. 7

Ans: C

Solution:

The pH of our digestive system is acidic due to the presence of HCl. Antacids are bases that give relief from pain and acidity. A common antacid used to treat indigestion is magnesium hydroxide.

Question. 8

Ans: D

Question.9

Ans: A

Solution: Zinc reacts with aqueous sodium hydroxide to form sodium zincate and hydrogen gas.

Zn + 2NaOH → Na2ZnO2 + H2

Question.10

Ans: C

Solution: A paste made of baking soda and water can help neutralize bee venom to reduce pain, itching, and swelling. Apply a thick layer of baking soda paste to the affected area.

Question.11

Ans: B

Solution:

Semiconductors are unique materials that have neither the electrical conductivity of a conductor nor of an insulator. They are made out pure silicon, that is essentially pure silicon crystal.

Silicon is perfect for making this lattice structure because its four valence electrons allow it too perfectly bond to four of its silicon neighbours.

Hence, the correct option is

Question.12

(a) (i) and (ii) (b) (i) and (iii)

Ans: A

Solution: Electrolytic refining is used for metals like Cu, Zn, Ag, Au etc. The method to be used for refining an impure metal depends on the nature of the metals well as on the nature of impurities present in it. So, metals Au (gold) and Cu (copper) are refined by electrolytic refining

Question.13

Ans: B

Solution: Gold (Au) and silver (Ag) are highly non-reactive metals. Therefore, they are available in their native state in nature as they do not react with oxygen or any other element in the atmosphere.

Question.14

Ans: D

Solution: Steel is an alloy that contains a non-metal carbon as one of its constituents.

Question.15

Ans: B

Solution: Graphite is a non-metal and it is the only non-metal that can conduct electricity.

Question.16

Ans: B

Solution: Stainless steel is an alloy of iron, chromium and nickel.

Question.17

Ans: A

Solution:

Copper metal and silver nitrate solution gives displacement reaction and the chemical equation can be written as:

$C u + 2 A g N O_{3} \to C u (N O_{3})_{_{2}}$ +2Ag

Question.18

Ans: C

Solution: Metal oxides which react with both acids as well as bases to produce salts and water are known as amphoteric oxides. Many metals (such as zinc, tin, lead, aluminium, and beryllium) form amphoteric oxides or hydroxides.

Question.19

Ans: D

Solution: Diamond and iodine are two exceptions and are lustrous non-metal.

Question.20

Ans: C

Solution: X is magnesium as it has atomic number 12. After losing two electrons, it will have 10 electrons with electronic configuration 2,8, which represents neon gas. So, neon gas is the nearest inert gas to X.

Question.21