Read the text carefully and answer the questions: The teacher whi… - Vidyadip

Question

Read the text carefully and answer the questions:
The teacher while conducting practicals in the laboratory divided the students into three groups and gave them various solutions to find out their pH and classify them into acidic, basic and neutral solutions.
Group A - Lemon juice, vinegar, colourless aerated drink
Group B - Tomato juice, coffee, ginger juice
Group C - Sodium hydroxide, sodium chloride, lime water
(a) For the solutions provided, which group is/are likely to have pH value (i) less than 7, and (ii) greater than 7?
(b) List two ways of determining pH of a solution.
OR
Explain, why the sour substances such as lemon juice are effective in cleaning the tarnished copper vessels.

✓

Answer

The teacher while conducting practicals in the laboratory divided the students into three groups and gave them various solutions to find out their pH and classify them into acidic, basic and neutral solutions.
Group A - Lemon juice, vinegar, colourless aerated drink
Group B - Tomato juice, coffee, ginger juice
Group C - Sodium hydroxide, sodium chloride, lime water
(i) i. Groups A and Bless than 7
ii. Group C - greater than 7
(ii) pH paper and universal indicator.
OR
i. Copper vessel is tarnished due to formation of basic copper oxide.
ii. Lemon juice being acidic react with copper oxide and the salt formed is washed away.

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Explore more

More "case /data -based (4 Marks)" from MODEL PAPER 1→MODEL PAPER 1 — all question types→Science STD 10 question papers→CBSE Board STD 10 question papers→CBSE Board question paper generator→

Similar questions

The pictures show the bonds formed by the sharing of electrons by the atoms of four different
molecules.

1. Which molecule has the strongest bond between its atoms?
A. Hydrogen
B. Carbon
C. Nitrogen
D. Oxygen
2. What is this type of bond between atoms known as?
3. Which of these is another way of representing the bonds between the atoms of a nitrogen molecule?
A. $N 0 N$
C. $N \equiv N$
B. $N \times N$
D. $N - N$
4. Which of these statements is true about carbon compounds?
Circle ‘Yes’ or ‘No’ for the correct response.

Is this true about carbon compounds?	Yes or No
They are good conductors of electricity.	Yes/No
They exist in either saturated or unsaturated form	Yes/No
They have lower boiling points than ionic compounds.	Yes/No

A pH paper changes its colour depending on the pH value of the substance it is dipped in.
The picture shows the different colours of a pH paper.

Leena tested the pH value of four liquids using a pH paper.
The table shows the shade of the pH paper after it is dipped separately in the four liquids.

	Liquid 1	Liquid 2	Liquid 3	Liquid 4
Shade of the pH paper	Colour 9	Colour 12	Colour 5	Colour 3

1. Which liquid has the lowest concentration of hydrogen ions?
A. Liquid 1
B. Liquid 2
C. Liquid 3
D. Liquid 4
2. Leena was advised by her teacher to wear gloves and use forceps while dipping the pH paper in the liquids.
What was the reason for this advice?
Circle ‘Yes’ or ‘No’ to mark your responses.

Is the reason correct?	Yes or No
Gloves keep the hands warm.	Yes/No
Forceps provide better grip than bare hands.	Yes/No
Gloves protect hands from corrosive liquids.	Yes/No

3. What should be the colour of a pH paper after it is dipped in distilled water?
Explain your answer.

An insulated copper wire wound on a cylindrical cardboard tube such that its length is greater than its diameter is called a solenoid. When an electric current is passed through the solenoid, it produces a magnetic field around it. The magnetic field produced by a current-carrying solenoid is similar to the magnetic field produced by a bar magnet. The field lines inside the solenoid are in the form of parallel straight lines. The strong magnetic field produced inside a current-carrying solenoid can be used to magnetize a piece of a magnetic material like soft iron when placed inside the solenoid. The strength of the magnetic field produced by a current-carrying solenoid is directly proportional to the number of turns and strength of the current in the solenoid.

(a) What would be the strength of the magnetic field inside a long current-carrying straight solenoid?
(b) Which end is north and which end is south pole when current flows through a solenoid?
(c) A long solenoid carrying a current produces a magnetic field B along its axis. If the current is double and the number of turns per cm is halved, then what will be the new value of the magnetic field?
OR
A soft iron bar is enclosed by a coil of insulated copper wire as shown in the figure. When the plug of the key is closed, then where would the face B of the iron bar be marked?

Salt of a strong acid and strong base is neutral with a pH value of 7. NaCl common salt is formed by a combination of hydrochloride and sodium hydroxide solution. This is the salt that is used in food. Some salt is called rock salt, bed of rock salt was formed when seas of bygone ages dried up. The common salt thus obtained is an important raw material for various materials of daily use, such as sodium hydroxide, baking soda, washing soda, and bleaching powder.
a. If given acids are phosphoric acid, carbonic acid, hydrochloric acid and sulphuric acid, then which acid
does not form an acidic salt?
b. What is the formula of baking soda?

OR

Name the substance which on treatment with chlorine to obtain bleaching powder

Riya wants to ind out how metal conducts heat.
She attaches four nails on a copper rod with wax.
Riya heats one end of the copper rod with a lame.

1. Which nail will fall last?
A. Nail 1
B. Nail 2
C. Nail 3
D. Nail 4
2. What should Riya keep the same in her activity?
A. Length of the nails
B. Material of the nails
C. Thickness of wax coatings
D. Distance between the nails

The picture shows the incomplete chain structure of a carbon compound.
The second carbon atom has two free electrons.

5. How many oxygen atoms can combine with the second carbon atom to complete the structure?
A. One
B. Two
C. Three
D. Fou
6. Which of these molecules contains a double bond?
A. CH₄
B. C₂H₄
C. C₃H₈
D. C₄H₁₀
A part of a homologous series is shown below.
C₃H₄, C₄H₆, C₅H₈
7. Which of these compounds is a part of the series shown above?
A. C₂H₂
B. C₂H₄
C. C₈H₆
D. C₆H₁₄

Read the following and answer any three questions from (i) to (iv).The heating effect of current is obtained by transformation of electrical energy in heat energy. Just as mechanical energy used to overcome friction is covered into heat, in the same way, electrical energy is converted into heat energy when an electric current flows through a resistance wire. The heat produced in a conductor, when a current flows through it is found to depend directly on (a) strength of current (b) resistance of the conductor (c) time for which the current flows. The mathematical expression is given by $\text{H} = \text{I}^2\text{Rt}.$
The electrical fuse, electrical heater, electric iron, electric geyser etc. all are based on the heating effect of current.

What are the properties of heating element?
What are the properties of electric fuse?
When the current is doubled in a heating device and time is halved, the heat energy produced will be?
OR
A) A fuse wire melts at 5 A. It is is desired that the fuse wire of same material melt at 10 A. The new radius of the wire will be.

B) When a current of 0.5A passes through a conductor for 5 min and the resistance of conductor is $10\Omega$ the amount of heat produced will be.

A student fixes a sheet of white paper on a drawing board using some adhesive materials. She places a bar magnet in the centre of it and sprinkles some iron filings uniformly around the bar magnet using a salt sprinkler. On tapping the board gently, she observes that the iron filings have arranged themselves in a particular pattern.
(a) What makes iron filings arrange in a definite pattern?
(b) Draw a diagram to show this pattern of iron filings.
(c) How is the direction of magnetic field at a point determined using the field lines? Why do two magnetic field lines not cross each other?
OR
How are the magnetic field lines of a bar magnet drawn using a small compass needle? Draw one magnetic field line each on both sides of the magnet.

Four combustion reactions of carbon compounds are shown below.
(i) CH₄+ O₂→ CO₂+ H₂O + heat
(ii) CH₃CHO + O₂→ CO₂+ H₂O + heat
(iii) CH₃CH₂CH₂OH + O₂→ CO₂+ H₂O + heat
(iv) C₆H₆+ O₂→ CO₂+ H₂O + heat
8. What can be concluded from the four reactions?
Circle ‘Yes’ or ‘No’ for the correct response.

Can this be concluded from the reactions?	Yes or No
All carbon compounds release oxygen on combustion.	Yes/No
All carbon compounds release water on reacting with oxygen.	Yes/No
All carbon compounds produce carbon dioxide on reacting with oxygen.	Yes/No

9. Which reaction shows the combustion of a type of alcohol?
A. Reaction i
B. Reaction ii
C. Reaction iii
D. Reaction iv

When light ray goes from one transparent medium to another transparent medium, it suffers a change in direction, into second medium. The extent of the change in direction suffered by the phenomenon of change in the path of light rays when going from one medium to another medium is known as refraction. Ray is a given pair of media can be expressed in terms of refractive index. The refractive index is related to an important physical quantity in the relative speed of light in different media.

<

(i) A ray of light enters into the glass from air. Does it bend towards normal ?
(ii) What is the unit of refractive index?
(iii) Light enters from air to glass having refractive index 1.50. What is the speed of light in the glass? The speed of light in vacuum is $3 \times 10^3 ms ^{-1}$.
or
(iii) When light goes from one medium to another, which of the three parameters, frequency, wavelength, velocity change?