Class 10 Science Chapter 5 MCQ for 2020-2021
| Class: 10 | Science |
| Chapter: 5 | Multiple Choice Questions (MCQ) Tests |
Class 10 Science Chapter 5 MCQ with Answers
MCQ tests practice for class 10 science is given below. Here, you can practice chapter 5 of class 10 science with important MCQs related to NCERT Textbook. Class 10 Science Chapter 5 MCQs are given below with answers and explanation.
Q1
Newlands’ law of octaves for the classification of elements had the following limitations. Choose the correct limitation:
[A]. Newlands assumed that only 56 elements existed in nature and no more elements would be discovered in the future.
[B]. Newlands’ law of octaves was applicable to the classification of elements up to calcium only.
[C]. In order to fit elements into his table, Newlands put even two unlike elements having very different properties.
[D]. All the above.
Answer: Option D
Explanation:Here, all the statements are correct. Hence, your answer will be option [D].
Q2
Consider the following statements and choose the incorrect one:
[A]. In Mendeleev’s periodic table, the elements are arranged on the basis of their atomic masses, atomic numbers and also on the similarity of chemical properties.
[B]. Dobereiner’s triads did not exist in the columns of Newlands’ classification of elements based on the law of octaves
[C]. The periodic table is a chart of elements prepared in such a way that the elements having different properties occur in the same vertical column but similar in group.
[D]. All the above.
Answer: Option D
Explanation:Here, all the statements are incorrect. Hence, your answer will be option [D].
Explanation: In option [A], In Mendeleev’s periodic table, the elements are arranged on the basis of their atomic masses and also on the similarity of chemical properties, whereas the modern periodic table is based on the atomic numbers of elements.
In option [B]: Dobereiner’s triads also exist in the columns of Newlands’ classification of elements based on the law of octaves.
In option [C]: The periodic table is a chart of elements prepared in such a way that the elements having similar properties occur in the same vertical column or group. It is called periodic because the elements having similar properties are repeated after certain intervals or periods; and it is called a table because the elements are arranged in the tabular form.
Q3
What type of oxide would Eka–Aluminium form?
[A]. EO3
[B]. E3 O2
[C]. E2O3
[D]. EO
Answer: Option C
Explanation:Gallium has a valency of 3. Hence, it forms an oxide having molecular formula E2O3. In other options, valency of E is not 3.
Note: Eka-Aluminium (first element after Aluminium) i.e. gallium lies in group III of the Mendeleev’s periodic table.
Q4
Read the following sentences carefully, and choose the incorrect one(s):
[A]. The horizontal rows of elements in a periodic table are called periods.
[B]. All other periods start with noble gases like neon, argon, krypton, etc. and end with alkali metals like lithium, sodium, potassium, etc.,
[C]. The elements in a period have consecutive (continuous) atomic numbers.
[D]. The figures 2, 8, 18, 32, etc., representing the maximum number of electrons which can be put in the various shells of the atoms.
Answer: Option B
Explanation:The first period starts with hydrogen and ends with noble gas helium. All other periods start with alkali metals like lithium, sodium, potassium, etc., and end with noble gases like neon, argon, krypton, etc.
Q5
Which one of the following does not increase while moving down the group of the periodic table?
[A]. Atomic radius
[B]. Metallic character
[C]. Valence
[D]. Number of shells in an element
Answer: Option C
Explanation:All the elements of a group of the periodic table have the same number of valence electrons. e.g., all the elements of group 1 have one valence electron each in their atoms.
All the elements of group 18 have 8 valence electrons each in their atoms, except helium which has only 2 valence electrons in its atom. All the remaining three properties increase down the group.
Note: On moving down in a particular group of the periodic table, the number of valence electrons in the elements remains the same. All the remaining three properties increase down the group.
Q6
An element which is an essential constituent of all organic compounds belongs to
[A]. Group 1
[B]. Group 14
[C]. Group 15
[D]. Group 16
Answer: Option B
Explanation:Constituent of all organic compounds is carbon. It belongs to group 14.
Q7
The elements A, B, C, D and E have atomic number 9, 11, 17, 12 and 13 respectively. Which pair of elements belongs to the same group?
[A]. A and B
[B]. B and D
[C]. A and C
[D]. D and E
Answer: Option C
Explanation:Electronic configuration of A (atomic number 9) is 2, 7.
Electronic configuration of B (atomic number 11) is 2, 8, 1.
Electronic configuration of C (atomic number 17) is 2, 8, 7.
Electronic configuration of D (atomic number 12) is 2, 8, 2.
Electronic configuration of E (atomic number 13) is 2, 8, 3.
Elements which differ in atomic number by 8 i.e., 9 (A fluorine) and 17 (Cl chlorine) lie in the same group i.e., group 17 (halogens).
Q8
Which of the following statements about the Modern Periodic Table is correct?
[A]. It has 18 horizontal rows known as Periods.
[B]. It has 7 vertical columns known as Periods.
[C]. It has 18 vertical columns known as Groups.
[D]. It has 7 horizontal rows known as Groups.
Answer: Option C
Explanation:Modern Periodic table has 18 vertical columns, known as groups and 7 horizontal rows, known as periods.
Q9
Sunakshi is completed her science chapter where she wrote some statements on “Periodic Table”. She wants to know whether the statements are correct or not? Sunakshi wants to take help from you:
[A]. In group 1 consists of alkali metals lithium, sodium, potassium, etc., all having 1 valence electron in their atoms.
[B]. In group 17 contains halogens like fluorine, chlorine, bromine and iodine, etc., all having 7 valence electrons.
[C]. Group 18 elements are known as noble gases or inert gases, all having 8 electrons in their outermost shells (except helium which has only 2 electrons in the K valence shell).
[D]. All the above.
Answer: Option D
Explanation:Here, all the statements are correct. Hence, your answer will be option [D].
Q10
Rahul is writing some statements about “Periodic Table”. Choose the correct one(s):
[A]. Elements having 6 valence electrons are placed in group 16.
[B]. Elements having 7 valence electrons are placed in group 17.
[C]. Elements having 8 valence electrons (or 2 valence electrons in K shell) are placed in group 18.
[D]. All the above.
Answer: Option D
Explanation:Here, all the statements are correct. Hence, your answer will be option [D].
why did Mendeléev select Oxygen and Hydrogen to test the chemical properties of elements?
Mendeléev selected hydrogen and oxygen to test the chemical properties of elements as they are very reactive and formed compounds with most elements.
What were the limitations of Mendeleev’s Periodic Law?
1. Isotopes of all elements posed a challenge to Mendeleev’s Periodic Law.
2. The atomic masses do not increase in a regular manner in going from one element to the next. So it was not possible to predict how many elements could be discovered between two elements — especially when we consider the heavier elements.
3. No proper place assigned to Hydrogen.
What is modern periodic law?
The modern periodic law states that Properties of elements are a periodic function of their atomic number.
What happen to atomic radius of atoms when we move from left to right in a period?
The atomic radius decreases in moving from left to right along a period. This is due to an increase in nuclear charge which tends to pull the electrons closer to the nucleus and reduces the size of the atom.
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