Lines and Angles — Mastery

Q1. When three points are marked on a piece of paper to distinguish them, the chapter suggests denoting each by

• A. A capital English letter such as Z, P or T
• B. A small English letter such as l or m
• C. A digit such as 1, 2 or 3
• D. A Hindi vowel such as अ, आ or इ

Q2. Rihan marks a single point on a piece of paper. How many different lines can he draw that pass through this point?

• A. Only one
• B. Exactly two
• C. Exactly four
• D. Infinitely many

Q3. The chapter introduces a line segment through which everyday activity?

• A. Folding a piece of paper and observing the crease
• B. Throwing a ball straight up
• C. Drawing a complete circle with a compass
• D. Watching a needle move on a clock

Q4. In Fig. 2.4 of the chapter, five marked points L, M, P, Q, R are joined to form four line segments LM, MP, PQ and QR. The total number of line segments in this figure is

• A. Three
• B. Four
• C. Five
• D. Six

Q5. A line segment AB consists of

• A. Only the points strictly between A and B
• B. Only the points A and B
• C. All the points from A to B, including A and B themselves
• D. All the points from A to B, but excluding A and B

Q6. Why can we not draw a complete picture of a line on a sheet of paper?

• A. Because lines cannot exist on paper
• B. Because a line extends without any end in both directions, but a sheet of paper is finite
• C. Because a line has no thickness, so it cannot be seen
• D. Because pencils cannot draw straight enough

Q7. Consider the following statements: I. A line segment has two endpoints. II. A ray has exactly one endpoint and extends in one direction. III. A line has no endpoints and extends in both directions. Which of the statements are correct?

• A. I and II only
• B. II and III only
• C. I and III only
• D. All three

Q8. A ray starts at O, passes through point A and continues through point B. By which other name can this ray be called?

• A. Ray AO
• B. Ray BA
• C. Ray AB
• D. Ray OB

Q9. The word ‘angle’ in the name of an angle can also be replaced by which symbol?

• A. ∠
• B. →
• C. ↔
• D. ○

Q10. In which of the following everyday objects does the chapter NOT explicitly identify an angle?

• A. A pair of open scissors
• B. An open wallet or spectacles
• C. The arms of a compass (divider)
• D. A perfectly round chapati

Q11. Vidya opens the cover of her book in six successive cases, where the cover is turned a little more each time from Case 1 to Case 6. Which case shows the largest angle?

• A. Case 1
• B. Case 2
• C. Case 3
• D. Case 6

Q12. ‘Rotating arms’ in the chapter are made using two paper straws and

• A. A rubber band
• B. A small piece of cardboard
• C. A paper clip
• D. A piece of chalk

Q13. In the ‘passing through a slit’ activity, a rotating arm passes through a cardboard slit only when

• A. Its arms are longer than the slit
• B. Its arms are shorter than the slit
• C. The angle between its arms equals the slit angle, irrespective of arm length (provided arms are shorter than the slit)
• D. The arms touch each other at the vertex

Q14. While comparing two angles by superimposition, which condition must be ensured first?

• A. Both arms of both angles must be of equal length
• B. The two angles must lie on the same sheet of paper
• C. The vertices of the two angles must overlap each other
• D. Both angles must already be drawn on a circle

Q15. Two angles are superimposed so that their vertices coincide and one arm of each lies along the other. The two angles are equal in size when

• A. The two angles have arms of the same length
• B. The remaining arms of the two angles also overlap exactly
• C. Both angles point in the same general direction
• D. One arm is shorter than the other

Q16. When comparing two angles without superimposing the figures themselves, the chapter suggests using a transparent circular paper. The centre of this circle must be placed on

• A. The vertex of each angle in turn
• B. The midpoint of one arm of the angle
• C. The endpoint of the longer arm only
• D. Any random point inside the angle

Q17. AOB is a straight angle. A ray OC is drawn from O so that ∠AOC = 70°. The measure of ∠COB is

• A. 110°
• B. 90°
• C. 70°
• D. 20°

Q18. Vidya places her book flat on the table by opening its cover through a half turn. The angle between the cover and the page is

• A. A straight angle, equal to 180°
• B. A right angle, equal to 90°
• C. An acute angle, less than 90°
• D. A reflex angle, greater than 180°

Q19. Make a slanting crease on a paper and then a second crease perpendicular to the first. How many right angles are formed where the two creases meet?

• A. Only one right angle
• B. Two right angles only
• C. Three right angles
• D. Four right angles, each equal to 90°

Q20. An angle measures 102° on a protractor. Its correct classification is

• A. Obtuse angle
• B. Acute angle
• C. Right angle
• D. Reflex angle

Q21. An angle measures 258°. The angle is

• A. An acute angle
• B. A right angle
• C. An obtuse angle
• D. A reflex angle

Q22. At 9 o'clock, the angle between the hour and minute hands of a clock, measured the long way around (the reflex side), equals

• A. 270°
• B. 180°
• C. 90°
• D. 60°

Q23. A straight angle AOB drawn on a side of a rectangular sheet is folded through O so that OB falls exactly along OA. The crease formed is

• A. A curve that passes through O
• B. Parallel to AB
• C. A second straight angle, larger than AOB
• D. The bisector of angle AOB, perpendicular to AB at O

Q24. A standard half-circle protractor has the straight angle at its centre divided into how many one-degree units?

• A. 180 units
• B. 90 units
• C. 360 units
• D. 100 units

Q25. To read an angle directly from a protractor (without using subtraction), one must

• A. Place the protractor at random and rotate the figure to fit
• B. Place the centre of the protractor on the midpoint of one arm
• C. Place either endpoint of an arm at the centre, in any direction
• D. Place the centre of the protractor on the vertex and align one arm with the 0° mark

Q26. Vidya wants to draw ∠TIN = 30° using a protractor. The very first step in the chapter is to

• A. Draw a base ray IN
• B. Place the protractor anywhere on the page
• C. Mark a point T at 30° on the page
• D. Bisect a straight angle to get 30°

Q27. A Class 6 student claims that an angle with longer arms must be larger than an angle with shorter arms. The best teacher response is to

• A. Ignore the comment because angle size is a senior-class topic
• B. Tell the student that he is right and move on with the lesson
• C. Ask the student to memorise the chapter summary
• D. Ask the student to make two rotating arms with the same angle but different arm lengths and superimpose them

Q28. Before cutting off a part of each arm of a drawn angle, a teacher first asks students to predict whether the angle will become smaller. This use of ‘predict, observe, explain’ is most useful because it

• A. Surfaces the students' existing misconception so it can be confronted
• B. Saves chalk and paper in the lesson
• C. Lets the teacher avoid using a protractor altogether
• D. Lets students copy the prediction from the textbook

Q29. A Class 6 teacher wants to introduce the concept of an angle for the first time. According to the chapter's spirit, the best opening activity is to

• A. Spend the period only naming famous mathematicians who studied angles
• B. Have students copy the textbook definition of an angle word for word
• C. Begin with formulas for angles in polygons
• D. Have students identify the arms and vertex on everyday objects such as scissors, spectacles and an open book

Q30. The chapter recommends that students make their own paper protractor by folding a circle before using the plastic one. The strongest reason for this sequence is that

• A. It helps students understand the meaning behind the markings on a standard protractor
• B. It removes the need to teach degrees at all
• C. It is faster than handing out plastic protractors
• D. It avoids the chapter's later activities on bisectors