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Identify the type of reactions taking place in each of the following cases and write the balanced chemical equation for the reactions: (a) Zinc reacts with silver nitrate to produce zinc nitrate and silver. (b) Potassium iodide reacts with lead nitrate to produce potassium nitrate and lead iodide.

(a) The given reaction is a displacement reaction in which more reactive zinc will displace less reactive silver from silver... View Article

Identify the acid and base which form sodium hydrogen carbonate . Write chemical equation in support of your answer. State whether its compound is acidic, basic or neutral. Also write its pH value.

Sodium hydroxide (NaOH) is the base and hydrogen carbonate (H2CO3) is the acid which forms sodium hydrogen carbonate (NaHCO3). NaOH + H2CO3 ⟶ NaHCO3 +... View Article

Write the structure of eye lens and state the role of ciliary muscles in the human eye.

Eye lens is a transparent fibrous jelly-like material bi-convex lens. The main function of the ciliary muscles used to change... View Article

Write the name, symbol and electronic configuration of an element X whose atomic number is 11.

According to the question, the chemical name of element X is sodium because its atomic number is 11. The Symbol... View Article

List four precautions which a student should observe while determining the focal length of a given convex lens by obtaining image of a distant object on a screen.

The four precautions which a student should observe while determining the focal length of a given convex lens by obtaining image of... View Article

While studying the dependence of potential difference (V) across a resistor on the current (I) passing through it, in order to determine the resistance of the resistor, a student took 5 readings for different values of current and plotted a graph between V and I. He got a straight line graph passing through the origin. What does the straight line signify? Write the method of determining the resistance of the resistor using this graph.

The straight-line graph of the potential difference (V) across a resistor on the current (I) passing through it signifies that the potential difference (V) is directly... View Article

Draw a labelled diagram in the proper sequence to show budding in hydra.

Hydra is exclusively a freshwater organism having different species. It is very small, just a half centimetre long. It is... View Article

A student is observing the temporary mount of a leaf peel under a microscope. Draw a labelled diagram of the structure of stomata as seen under the microscope.

Epidermal Cell: It is the outermost layer of plants. These specialized cells originate from the dermal tissues of the plant. Epidermal... View Article

In three test tubes A, B and C, three different liquids namely, distilled water, underground water and distilled water in which a pinch of calcium sulphate is dissolved, respectively are taken. An equal amount of soap solution is added to each test tube and the contents are shaken. In which test tube will the length of the foam (lather) be longest? Justify your answer.

The length of the foam (lather) will be the longest in test tube A, which contains only distilled water. This... View Article

What is observed when 2 mL of dilute hydrochloric acid is added to 1 g of sodium carbonate taken in a clean and dry test tube? Write the chemical equation for the reaction involved.

A brisk effervescence would be observed if HCl is added to Na2CO3 due to the evolution of CO2 gas. Na2CO3 + HCl → NaCl... View Article

Blue litmus solution is added to two test tubes A and B containing dilute HC1 and NaOH solution respectively. In which test tube a colour change will be observed? State the colour change and give its reason.

Blue litmus turns red when it comes in contact with an acid. So Test tube A containing HCl will change... View Article

An electric lamp of resistance 20 Ω and a conductor of resistance 4 Ω are connected to a 6 V battery. (a) the total resistance of the circuit, (b) the current through the circuit, (c) the potential difference across the (i) electric lamp and (ii) conductor, and (d) power of the lamp.

Resistance of electric lamp, R1 = 20Ω Resistance of conductor, R2 = 4Ω Voltage, V=6V To find: (a) the total resistance of the circuit, RT. (b) the current... View Article

In an electric circuit two resistors of 12 Ω each are joined in parallel to a 6 V battery. Find the current drawn from the battery.

Resistance of first resistor = R1 = 12Ω Resistance of second resistor = R2 = 12Ω Voltage, V = 6V I = ? Solution: We... View Article

With the help of a suitable circuit diagram prove that the reciprocal of the equivalent resistance of a group of resistances joined in parallel is equal to the sum of the reciprocals of the individual resistances.

The figure given above shows a circuit consisting of three resistors R1, R2, and R3 connected in parallel to a battery of voltage V. Suppose the... View Article

An object is placed at a distance of 60 cm from a concave lens of focal length 30 cm. (i) Use the lens formula to find the distance of the image from the lens. (ii) List four characteristics of the image (nature, position, size, erect/inverted) formed by the lens in this case. (iii) Draw ray diagram to justify your answer of the part (ii).

Object distance = u = − 60 cm Focal length = f = − 30 cm To find: Distance of the image from the lens, v. Solution: Using lens formula,... View Article

What is contraception? List three advantages of adopting contraceptive measures.

Contraception is an artificial method practised avoiding pregnancy during sexual intercourse. The contraception method prevents pregnancy by either restricting the... View Article

Identify the given diagram. Name the parts 1 to 5.

1. Fallopian tube The primary role of the fallopian tubes is to transport eggs from the ovaries to the uterus.... View Article

Define pollination. Explain the different types of pollination. List two agents of pollination? How does suitable pollination lead to fertilization?

Pollination can be defined as the pre-fertilization event or process where pollen grains from anther are transferred to the stigma... View Article

Write the chemical formula and name of the compound which is the active ingredient of all alcoholic drinks. List its two uses. Write chemical equation and name of the product formed when this compound reacts with (i) sodium metal (ii) hot concentrated sulphuric acid

Ethyl alcohol or Ethanol is the active ingredient in all alcoholic drinks. Its formula is C2H5OH. Uses: Ethanol is used... View Article

Give reasons for the following: (i) Most metals conduct electricity well. (ii) The reaction of iron (III) oxide [Fe2O3] with heated aluminium is used to join cracked machine parts.

(i) The outer electrons of metal atoms are not tied to any one atom. Therefore, these electrons are free to move... View Article

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