Acids, Bases and Salts — Science STD 10 — Question

The indicator which produces a pink colour in an alkaline solution is:

1. Methyl orange.
2. Turmeric paper.
3. Phenolphthalein.
4. Litmus paper.

The aqueous solutions of copper sulphate and zinc sulphate appear:

In Mendele′ ev ’s Periodic Table, gaps were left for the elements to be discovered later. Which of the following elements found a place in the perioidc table later:

1. Germanium.
2. Chlorine.
3. Oxygen.
4. Silicon.

A student takes four test tubes marked P, Q, R and S of 25 mL capacity and fill 10 mL of distilled water in each. He dissolves one spoon full of four different salts in each as – KCl in P, NaCl in Q, CaCl₂ in R and MgCl₂ in S. He then adds about 2 mL of a sample of soap solution to each of the above test tubes. On shaking the contents of each of the test tubes, he is likely to observe a good amount of lather (foam) in the test tubes marked:

On the basis of the sequence of the given reactions identify the most and least reactive elements:
X + YA → XA + Y ...(i)
X + YB → XB + Y ...(ii)
Z + XA → ZA + X

Which of the following statements is true for an amphoteric oxide?

Oils on treating with hydrogen in the presence of palladium or nickel catalyst form fats. This is an example of:

1. Addition reaction.
2. Substitution reaction.
3. Displacement reaction.
4. Oxidation reaction.

The molecular formula of an organic compound is C₄₈H_94. This compound belongs to the homologous series of:

The only liquid metal at the room temperature:

The daffodil plants grow best in a soil having a pH range of 6.0 to 6.5. If the soil in a garden has a pH of 4.5, which substance needs to be added to the soil in order to grow daffodils?

1. Salt.
2. Lime.
3. Sand.
4. Compost.