Rrb Technician Grade 3 Science Quiz 1 includes questions for chemistry subject important for all railways exam #ntpc #techniciangrade3 #ssc
Rrb Technician Grade 3 Science Quiz 1
1.In a shell, the maximum number of electrons is denoted by the formula:
(a) 2n²
(b) n²
(c) 2n
(d) n
Answer:
(a) 2n²
Explanation: According to the formula 2n², where n is the shell number, the maximum number of electrons in any shell can be calculated.
2.
Which of the following elements has the electronic configuration 2, 8, 4?
(a) Ar
(b) P
(c) Cl
(d) Si
Answer:
(d) Si
Explanation: Silicon (Si) has an atomic number of 14. Its electronic configuration is 2, 8, 4.
3.
How many total electrons are included in the electronic configuration of carbon?
(a) Four
(b) Two
(c) One
(d) Three
Answer:
(b) Two
Explanation: Carbon’s electronic configuration is 2, 4, meaning 2 electrons in the inner shell and 4 in the outer shell.
4.
The number of electrons in the outermost shell is called:
(a) Valence electrons
(b) Combined electrons
(c) Free electrons
(d) Bonding electrons
Answer:
(a) Valence electrons
Explanation: Valence electrons are the electrons in the outermost shell of an atom that participate in chemical bonding.
5.
Excluding helium, which noble gas has the highest number of electrons in its outermost shell?
(a) 10
(b) 8
(c) 4
(d) 18
Answer:
(b) 8
Explanation: Noble gases like neon, argon, and others (except helium) have 8 valence electrons in their outermost shell.
6.
What is the number of electrons in the outermost shell of the atoms of inert gases?
(a) 6
(b) 4
(c) 8
(d) 10
Answer:
(c) 8
Explanation: Inert gases have a complete octet (8 electrons) in their outermost shell, making them stable.
7.
An element with electronic configuration 2, 8, 8 belongs to which group?
(a) 16
(b) 18
(c) 8
(d) 17
Answer:
(b) 18
Explanation: The configuration 2, 8, 8 belongs to noble gases, which fall under Group 18.
8.
Which element has an electronic configuration of 2, 8, 5?
(a) Boron
(b) Sulfur
(c) Phosphorus
(d) Carbon
Answer:
(c) Phosphorus
Explanation: Phosphorus has an atomic number of 15. Its electronic configuration is 2, 8, 5.
9.
What is the maximum number of electrons that can fit in the valence shell?
(a) 4
(b) 2
(c) 8
(d) 6
Answer:
(c) 8
Explanation: According to the octet rule, a maximum of 8 electrons can occupy the valence shell of an atom.
10.
Which of the following elements has only one electron in its outermost shell?
(a) Lithium, Sodium, Potassium
(b) Magnesium, Calcium, Beryllium
(c) Hydrogen, Oxygen, Helium
(d) Aluminum, Silicon, Phosphorus
Answer:
(a) Lithium, Sodium, Potassium
Explanation: These elements belong to Group 1 and have one electron in their outermost shell.
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11.
What is the process of separating hydrogen and oxygen from water called?
(a) Electrolysis
(b) Osmosis
(c) Fractionation
(d) None of these
Answer:
(a) Electrolysis
Explanation: Electrolysis is the process of breaking water into hydrogen and oxygen using an electric current.
12.
Which of the following is not an example of a crystalline substance?
(a) Sodium chloride
(b) Copper
(c) Ammonium chloride
(d) Glass
Answer:
(d) Glass
Explanation: Glass is an amorphous substance and does not have a crystalline structure.
13.
Which of the following can undergo sublimation?
(a) Ammonium chloride
(b) Ammonium carbonate
(c) Ammonium sulfate
(d) Ammonium phosphate
Answer:
(a) Ammonium chloride
Explanation: Ammonium chloride changes directly from solid to gaseous form through sublimation.
14.
What process is used to separate ammonium chloride from a mixture of ammonium chloride and sodium chloride?
(a) Fractional distillation
(b) Sublimation
(c) Distillation under reduced pressure
(d) Filtration
Answer:
(b) Sublimation
Explanation: Sublimation is used to separate ammonium chloride as it changes directly to a gaseous state when heated.
15.
Which of the following is a mixture that can be separated by the method of decantation?
(a) Oil and water
(b) Saltwater
(c) Vinegar and water
(d) Alcohol and water
Answer:
(a) Oil and water
Explanation: Decantation is used to separate immiscible liquids like oil and water.
16.
Which technique is used for desalination of seawater?
(a) Distillation
(b) Sublimation
(c) Sedimentation
(d) Filtration
Answer:
(a) Distillation
Explanation: Distillation removes salt and other impurities from seawater to make it drinkable.
17.
Which method is used to separate ammonium chloride and sodium chloride from a mixture?
(a) Filtration
(b) Sublimation
(c) Sedimentation
(d) Distillation
Answer:
(b) Sublimation
Explanation: Sublimation separates ammonium chloride as it directly transitions from a solid to a gaseous state.
18.
Which factor affects the rate of evaporation the most?
(a) Temperature
(b) Surface area
(c) Wind speed
(d) All of these
Answer:
(d) All of these
Explanation: Temperature, surface area, and wind speed all influence the rate of evaporation significantly.
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