The device used to measure the rate of current in a circuit is
a.
Ammeter
Correct Answer
b.
Voltmeter
c.
Galvanometer
d.
Battery
Step-by-Step AI Explanation
Verified Method
An ammeter is specifically designed to measure the rate of flow of electric current (amperes) in a circuit. Voltmeters measure potential difference (voltage), galvanometers detect small currents, and batteries are sources of electric energy, not measuring devices.
Q2mcq1 mark
Observe the given figure. Identify the eye defect indicated in this figure.
a.
Presbyopia
b.
Hypermetropia
c.
Myopia
Correct Answer
d.
Cataract
Step-by-Step AI Explanation
Verified Method
In the provided image, the light rays are converging at a point in front of the retina. This is characteristic of myopia (nearsightedness), where the eyeball is too long or the lens is too powerful, causing images of distant objects to focus before the retina.
Q3mcq1 mark
A light ray enters to rarer medium from a denser medium. Then the speed of that light ray
a.
decreases and bends towards the normal
b.
increases and bends away from the normal
Correct Answer
c.
decreases and bends away from the normal
d.
increases and bends towards the normal
Step-by-Step AI Explanation
Verified Method
When light travels from a denser to a rarer medium, its speed increases. Due to this change in speed, it bends away from the normal line.
Q4mcq1 mark
The inner wall of the solar cooker is painted black. Because black colour
a.
reflects light
b.
converges solar rays
c.
prevents from rusting
d.
absorbs more heat
Correct Answer
Step-by-Step AI Explanation
Verified Method
Black surfaces are excellent absorbers of thermal radiation. Painting the inner wall of a solar cooker black ensures that the maximum amount of solar heat energy is absorbed, which is then used to cook the food inside.
Q5short answer1 mark
Write the symbols of the following components used in an electric circuit.
i) Rheostat
ii) Wires crossing without joining
Step-by-Step AI Explanation
Verified Method
i) Rheostat: A zig-zag line or rectangle with an arrow passing through it or touching the top.
ii) Wires crossing without joining: Two lines crossing each other, with one line having a small semi-circular loop over the point of intersection.
Q6short answer1 mark
What does the thumb indicate in the right hand thumb rule ?
Step-by-Step AI Explanation
Verified Method
In the Right-Hand Thumb Rule, the thumb indicates the direction of the electric current flowing through a straight conductor.
Q7short answer2 marks
Light enters from air to benzene having refractive index 1.50. Calculate the speed of light in benzene.
( Speed of light in air : $3 \times 10^8 \text{ ms}^{-1}$ )
Step-by-Step AI Explanation
Verified Method
Given, refractive index of benzene ($n$) = $1.50$. Speed of light in air ($c$) = $3 \times 10^8 \text{ ms}^{-1}$. The formula for the refractive index is $n = \frac{c}{v}$, where $v$ is the speed of light in the medium. Therefore, $v = \frac{c}{n} = \frac{3 \times 10^8}{1.50} = 2 \times 10^8 \text{ ms}^{-1}$. The speed of light in benzene is $2 \times 10^8 \text{ ms}^{-1}$.
Q7short answer2 marks
OR
A concave lens has focal length of 12 cm. At what distance should the object from the lens be placed so that it forms an image at 9 cm from the lens ?
Step-by-Step AI Explanation
Verified Method
For a concave lens, the focal length ($f$) is $-12 \text{ cm}$ and the image distance ($v$) is $-9 \text{ cm}$ (since the image formed by a concave lens is virtual and on the same side as the object). Using the lens formula $\frac{1}{f} = \frac{1}{v} - \frac{1}{u}$, we get $\frac{1}{-12} = \frac{1}{-9} - \frac{1}{u}$. Rearranging gives $\frac{1}{u} = \frac{1}{12} - \frac{1}{9} = \frac{3-4}{36} = \frac{-1}{36}$. Thus, $u = -36 \text{ cm}$. The object should be placed at a distance of $36 \text{ cm}$ from the lens.
Q8short answer2 marks
Name the major constituent of biogas and write the properties of biogas.
Step-by-Step AI Explanation
Verified Method
The major constituent of biogas is Methane ($CH_4$). Properties of biogas: 1. It is a clean fuel that burns without smoke. 2. It has a high calorific value. 3. It leaves no residue like ash after combustion. 4. It is eco-friendly and produced from organic waste.
Q8short answer2 marks
OR
List the hazards of nuclear power generation.
Step-by-Step AI Explanation
Verified Method
The hazards of nuclear power generation are: 1. Improper nuclear waste storage and disposal leads to environmental contamination. 2. High risk of accidental leakage of radioactive radiation, which is extremely harmful to living organisms. 3. High cost of setting up and maintaining nuclear reactors. 4. Limited availability of nuclear fuel.
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The resistors $R_1$, $R_2$ and $R_3$ have the values 10 $\Omega$, 20 $\Omega$ and 60 $\Omega$ respectively, which have been parallelly connected to a battery of 24 V in an electric circuit. Then calculate the following :
i) The current flowing through each resistor
ii) The total current in the circuit
iii) The total resistance of the circuit.
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Draw the ray diagram for the image formation in a convex lens when the object is placed beyond $2F_1$. Mention the position and nature of the image formed.
[$F_1$ : Principal focus of the lens ]
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a) What is solenoid ? Write the properties of the magnetic field lines formed around a current carrying solenoid.
b) What is alternating current ? Electric appliances having metallic body are connected to earth wire, why ?
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a) How does rainbow form in the nature ? Explain. Mention the colour of the light that bends the most and that bends the least.
b) How does the eye lens accommodate to see the distant objects and nearby objects ? Explain.
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The general formula of cycloalkanes is $C_nH_{2n}$ and its first member is cyclopropane ($C_3H_6$). Write the molecular formula and structural arrangement of the fourth member of this homologous series.
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The resistors $R_1$, $R_2$ and $R_3$ have the values $10 \, \Omega$, $20 \, \Omega$ and $60 \, \Omega$ respectively, which have been parallelly connected to a battery of 24 V in an electric circuit. Then calculate the following: i) The current flowing through each resistor
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“Calcium oxide and carbon dioxide are produced on heating calcium carbonate.” Write the balanced chemical equation for this reaction. Mention the type of this chemical reaction.
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a) Depict the formation of magnesium chloride with the help of electron dot structure. b) Hydrogen gas is not liberated when a metal like zinc reacts with nitric acid. Why ? OR How are metals in the middle of the reactivity series extracted from their ores ? Explain.
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a) Observe the given part of the modern periodic table and answer the following questions : i) Which element is more electropositive ? Why ? ii) Atoms of which element have minimum atomic radius ? Why ? b) Mention the period and group number of the element that has atomic number 19.
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Name the salts used in the following situations and write their molecular formula : a) To remove permanent hardness of water. b) To make drinking water free from germs. c) To support fractured bones in their right position. OR a) The pH values of four solutions are given in the below table. Classify these into acidic and basic solutions e, f, g, h into acidic and basic solutions : [Table data: e=5, f=13, g=9, h=2] b) Name the antacid used to neutralise excess of acid in the stomach.
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The pH values of four solutions are given in the below table. Classify these into acidic and basic solutions :
Solution | pH Value
--- | ---
e | 5
f | 13
g | 9
h | 2
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Give an example for a food chain of grassland ecosystem. If there is an increase in the number of organisms in the second trophic level, how does this affect on that food chain ?
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Tall pea plant producing red flowers ($TT RR$) is crossed with short pea plant producing white flowers ($tt rr$). Mention the type of plants produced from these plants in the $F_1$ generation.
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Tall pea plant producing red flowers ($TT RR$) is crossed with short pea plant producing white flowers ($tt rr$). Write the ratio of plants obtained in the $F_2$ generation by crossing the plants of $F_1$ generation and name the varieties of plants obtained.
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Analyse the situations given below. Situation 1: The number of green grasshoppers in a green zone has been increasing from one generation to another generation. Situation 2: The number of brown grasshoppers in the same green zone has been reducing. Where could genetic drift be happened more ? Why ?
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