make test of ncert class 8 maths of chapter 1
at least 20 mcq
and follow me for points
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Answers
Answer:
Here is your test 1 Question=2marks
Step-by-step explanation:
1. What are the multiplicative and additive identities of rational numbers?
Solution: 0 and 1 are the additive and multiplicative identity of rational numbers respectively.
2. Write the additive inverse of 19/-6 and -⅔
Solution: 19/-6 = 19/6 and -⅔ = 2/3
3. Write the multiplicative inverse of -13/19 and -7
Solution: -13/19 = -19/13 and -7 = -1/7
4. Mention a rational number which has no reciprocal.
Solution: A rational number “0” has no reciprocal or multiplicative inverse.
5. Mention any 4 rational numbers which are less than 5.
Solution: 0, 1, 2 and 3.
Long Answer Type Questions:
6. Mention the commutativity, associative and distributive properties of rational numbers. Also, check a × b = b × a and a + b = b + a for a = ½ and b = ¾
Solution: Commutative identity: a + b = b+ a, a – b ≠ b – a, a × b = b × a and a ÷ b ≠ b ÷ a
Associative property: a + (b + c), a – (b – c) ≠ (a – b) – c, a × (b × c) = (a × b) × c, and a ÷ (b ÷ c) ≠ (a ÷ b) ÷ c
When a = ½ and b = ¾
Now, for checking a × b = b × a, consider LHS and RHS.
LHS = a × b = ½ × ¾ = ⅜
RHS = b × a = ¾ × ½ = ⅜
Thus, LHS = RHS (Hence proved).
7. Write any 5 rational numbers between −2/5 and ½.
Solution: To find rational numbers between any two numbers, make the denominator same first.
So, −2/5 ⇒ (−2×10)/ (5×10) = −20/50
And, ½ ⇒ (1×25)/ (2×25) = 25/50
Now, 5 rational numbers between −2/5 and ½ = 5 rational numbers between −20/50 and 25/50 So, 5 rational numbers = −18/50, −15/50, −2/50, 8 /50, and 20/50
8. If the product of any two rational numbers is 2 and one of them is 1/7, find the other?
Solution: Consider 2 rational numbers as “a” and “b”.
Given, a = 1/7 and a × b = 2
Now, 1/7 × b = 2
⇒ b = 7 × 2 = 14
So, the other rational number will be 14.
9. Mr X went shopping with a certain amount of money. He spent Rs. 10(¼) on buying a pen and Rs. 25(¾) in food. He then gave the remaining Rs. 16(½) to his friend. Calculate how much money he initially had.
Solution: To get the amount of money Mr X had initially, his purchases have to be added.
So,
Initial Money = 10(¼) + 25(¾) + 16(½)
= 41/4 + 103/4 + 33/2
By taking LCM, we get
Initial Money = 210/4
10. Represent −/, −/, and −/ on the number line.
Solution: To represent these numbers, divide the number line into 11 parts. Now, the given rational numbers will be 2, 5 and 9 points away from 0.
Answer:
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Step-by-step explanation:
arrange in descending order_
1. -2,-13/6,-8/3,1/3
2.-3/10,7/-15,-11/20,17/-30
arrange in ascending order
3. 4/-9,-5/12,7/-18,-2/3
4.-3/4,5/-12,-7/16,9/-24
add
5.-2/5+4/5
6.-11/8+5/8
verify
7.-12/5+2/7=2/7+-12/5
8. the sum of 2 rational no. is -2.if one no.is -14/5, find the other.
THESE ARE NOT MCQ BUT VERY IMPORTANT BASIC QUESTIONS