Give practical application of spreading of liquid over solid.
[ Hint. Resin is used with solder is a tin-lead alloy )in soldering etc.]

Match the properties and uses of alloys in List 1 with the appropriate answer from List 2. List 1. The alloy contains Cu and Zn, is List hard and is used in decorative articles 2. It is stronger than Aluminium, light and is used in making light tools. 3. It is lustrous, hard corrosion resistant and used in surgical instruments. 4. Tin lowers the melting point of the alloy and is used for soldering purpose 5. The alloy is hard, brittle takes up polish and is used for making statues. List 2 : A. Duralumin B Brass C. Bronze D. Stainless Steel E. Solder

With its very large population of vehicular traffic, Delhi is one of the most polluted cities of the world. Which of the following steps were taken by the government to reduce vehicular pollution in Delhi ? (i) Switching over the entire fleet of public transport i.e., buses, autorickshaws, from diesel to CNG (ii) Phasing out of old vehicles (iii) Use of unleaded petrol in vehicles (iv) Use of low sulphur petrol and diesel in vehicles (v) Use of catalytic converters in vehicles (vi) Application of stringent pollution level norms for vehicles such as Euro-II norms, etc.

Name the following An alloy of lead and tin that is used in electrical circuits.

Match (A) cathode, (B) bauxite, (C) electrolytic reduction, (D) fuse metal, (E) gold, (F) cinnabar with its most correct description (i) - (vi) as given below. (i) It is an ore of a metal which is the major constituent of magnalium. (ii) Cations are reduced here. (iii) It is used to solder metal wires. (iv) It is an ore of metal which exists as liquid at room temperature. (v) It is most malleable. (vi) It is employed to isolate the metals high up in the activity series.

It is not possible to measure the atomic radius precisely since the electron cloud surrounding the atom does not have a sharp boundary. One practical approach to estimate the size of an atom of a non-metallic element is to measure the distance between two atoms when they are bound together by a single bond in a covalent molecule and then dividing by two. For metals we define the term "metallic radius" which is taken as half the inter nuclear distance separating the metal cores in the metallic crystal. Then van der waal's radius represents the over all size of the atoms which includes its valence shell in a non bonded situation. It is the half of the distance between two similar atoms in separate molecules in a solid. The atomic radius decreases across a period and increases down the group. Same trends are observed in case of ionic radius. Ionic radius of the species having same number of electrons depends on the number of protons in their nuclei. Sometimes, atomic and ionic radii give unexpected trends due to poor shielding of nuclear charge by d -and f- orbital electrons. Now answer the following three questions: Which of the following relations is correct, if considered for the same element.

It is not possible to measure the atomic radius precisely since the electron cloud surrounding the atom does not have a sharp boundary. One practical approach to estimate the size of an atom of a non-metallic element is to measure the distance between two atoms when they are bound together by a single bond in a covalent molecule and then dividing by two. For metals we define the term "metallic radius" which is taken as half the inter nuclear distance separating the metal cores in the metallic crystal. Then van der waal's radius represents the over all size of the atoms which includes its valence shell in a non bonded situation. It is the half of the distance between two similar atoms in separate molecules in a solid. The atomic radius decreases across a period and increases down the group. Same trends are observed in case of ionic radius. Ionic radius of the species having same number of electrons depends on the number of protons in their nuclei. Sometimes, atomic and ionic radii give unexpected trends due to poor shielding of nuclear charge by d -and f- orbital electrons. Now answer the following three questions: K^(+), CI^(-), Ca^(2+), S^(2-) ions are isoelectronic. The decreasing order of their size is:

When hydrogen is passed over a black solid compound A, the products are .a colourless liquid. and .a reddish brown metal B.. Substance B is divided into two parts, each placed in separate test tubes. Dilute HCl is added to one part of substance B and dilute HNO_3 to the other. Give two tests for the colourless liquid formed in the experiment. What does it signifies ?

When hydrogen is passed over a black solid compound A, the products are 'a colourless liquid' and 'a reddish brown metal B.' Substance B is divided into two parts, each placed in separate test tubes. Dilute HCl is added to one part of substance B and dilute HNO, to the other. What happens to substance A when it reacts with hydrogen ? Give reasons for your answer.

When hydrogen is passed over a black solid compound A, the products are 'a colourless liquid' and 'a reddish brown metal B.' Substance B is divided into two parts, each placed in separate test tubes. Dilute HCl is added to one part of substance B and dilute HNO, to the other. Is there any reaction between substance B and dilute hydrochloric acid ? Give reasons for your answer.

When hydrogen is passed over a black solid compound A, the products are .a colourless liquid. and .a reddish brown metal B.. Substance B is divided into two parts, each placed in separate test tubes. Dilute HCl is added to one part of substance B and dilute HNO_3 to the other. Is there any reaction between substance B and dilute hydrochloric acid ? Give reasons for your answer.