Chemistry MCQs
Chemistry Objective (Multiple Choice) General Knowledge Questions & Answers for SSC-CGL, UPPSC, UPSC, NDA, CDS and UPSC Civil Services Prelims Examination. These questions are part of GKToday’s 35000+ MCQs Bank Course in GKToday Android App
21. Which of the following is a chemical formula of quicklime?
[A] Ca2CO3
[B] CaO
[C] Ca2O
[D] CaO2
Show Answer
Correct Answer: B [CaO]
Notes:
Calcium oxide (CaO), commonly known as quicklime or burnt lime, is a widely used chemical compound. It is a white, caustic, alkaline, crystalline solid at room temperature.
22. What are the main components of Brass Alloy?
[A] Copper and Strontium
[B] Copper, Zinc and Nickel
[C] Copper and Nickel
[D] Copper and Zinc
Show Answer
Correct Answer: D [Copper and Zinc]
Notes:
Brass is an alloy made primarily of copper and zinc. The proportions of the copper and zinc are varied to yield many different kinds of brass. Basic modern brass is 67% copper and 33% zinc.
23. Most liquids that conduct electricity are solutions of acids, base and which of the following?
[A] Aluminium
[B] Copper
[C] Iron
[D] Salts
Show Answer
Correct Answer: D [Salts]
Notes:
Solutions that contain ions are good conductors of electricity, such as, acids, bases, salt water. Tap water, lemon juice and mercury is the best liquid conductor compare with others. Because of any solution to conduct, you need ions or free electrons.
24. Which of the following is correct for tea?
[A] Alkaline and nicotine
[B] Alkaline and caffeine
[C] Acidic and nicotine
[D] Acidic and caffeine
Show Answer
Correct Answer: B [Alkaline and caffeine]
Notes:
Black tea was found to have a pH of 6.37 and it contains caffeine while coffee had a pH of 5.35. The acidity level for tea and coffee also depends on where you’re getting it from.
25. The colour of an opaque object is due to the colour it?
[A] absorbs
[B] refracts
[C] reflects
[D] scatters
Show Answer
Correct Answer: C [reflects]
Notes:
The apparent color of an opaque object depends on the wavelength of the light that it reflects; e.g., a red object observed in daylight appears red because it reflects only the waves producing red light. The color of a transparent object is determined by the wavelength of the light transmitted by it.
26. Besides proteins and carbohydrates which of the following other elements of nutritional value found in milk?
[A] Calcium, potassium and iron
[B] calcium and potassium
[C] potassium and iron
[D] calcium and iron
Show Answer
Correct Answer: B [calcium and potassium]
Notes:
Besides proteins and carbohydrates, approximately 67% of calcium, 35% of magnesium and 44% of the potassium are found in milk.
27. Which of the following chemists helped to develop notation for writing chemical formulas?
[A] Amedeo Avogadro
[B] Jons Jacob Berzelius
[C] Marie Curie
[D] Robert Boyle
Show Answer
Correct Answer: B [Jons Jacob Berzelius]
Notes:
Jons Jacob Berzelius (1779 – 1848) was a Swedish chemist who is most famous for helping to develop the notation for writing chemical formulas. He also played a role in discovering and isolating many elements including silicon, thorium, cerium, and selenium. Many chemical terms are credited to Berzelius such as “allotrope” and “catalysis.” He is called the father of Swedish chemistry.
28. Which of the following is correct electronic configuration of Krypton, whose atomic number is 36?
[A] 2, 18,16
[B] 2,8,18,8
[C] 2,18,8,8
[D] 2,8,20,6
Show Answer
Correct Answer: B [2,8,18,8]
Notes:
Krypton is a chemical element with symbol Kr and atomic number 36. It is a member of group 18 (noble gases) elements. The electronic configuration of Krypton is [2, 8, 18, 8]
29. Which of the following is a natural dye?
[A] Crystal violet
[B] Aniline blue
[C] Alizarin
[D] Phenolphthalein
Show Answer
Correct Answer: C [Alizarin]
Notes:
Alizarin or 1,2-dihydroxyanthraquinone (also known as Mordant Red 11 and Turkey Red is an organic compound with formula C14 H8 O4 that has been used throughout history as a prominent red dye, principally for dyeing textile fabrics. Historically it was derived from the roots of plants of the madder genus. In 1869, it became the first natural pigment to be duplicated synthetically.
30. What percentage of carbon is present in steel?
[A] 0.0 to 2.5
[B] 2.5 to 5.0
[C] 5.0 to 7.5
[D] 7.5 to 10.0
Show Answer
Correct Answer: A [0.0 to 2.5 ]
Notes:Steel is an alloy made by combining iron and other elements, the most common of these being carbon. When carbon is used, its content in the steel is between 0.2% and 2. 1% by weight, depending on the grade. Other alloying elements sometimes used are manganese, chromium, vanadium and tungsten. Carbon and other elements act as a hardening agent, preventing dislocations in the iron atom crystal lattice from sliding past one another.
