[" (a) Electronegativity "],[" (a) First in inition energy "],[" As compared to lithium,sodum reacts quildy with water "],[" because "],[" (a) Its molecular weight is less "],[" (b) It is stronger electronegative "],[" (d) It is a metal "],[" Which is an ore of potassium (DPMT 1984; CPMT "1986" ."]

(1) Metals occur in the native form because of their (a) High electronegativity (b) Low reactivity ( c) Low density (d) High reactivity (2) Specific gravity of slag is (a) Higher than molten metal (b) Same as that of molten metal ( c) Less as that of molten metal (d) None of the above (3) Which process is used for the extraction of metals from their sulphide ores ? (a) Smelting Froth flotation ( c) Electrolysis (d) Metal displacement (4) Calamine is an ore of (a) Hg (b) Zn ( c) Ca (d) Cd (5) Non-fusible impurities of ores removed by adding Slag (b) Flux ( c) Gangue (d) None (6) Common method of extraction of metals from oxide ore involves. (a) Reduction with aluminium (b) Reduction with carbon Reduction with hydrogen (d) Electrolytic method (7) Smelting is the reduction of oxide to metal by (a) Carbon (b) Hydrogen ( c) Aluminimum (d) Electric current During froth flotation process, commonly used frother is. (a) CuSO_(4) (b) NaCN + alkali ( c) Pine oil (d) Potassium xanthate (9) Iron ores are dressed by (a) Froth flotation process (b) Hand picking ( c) Magnetic separation (d) All of the above (10) Silicon is the main constituent of (a) Alloys (b) Rocks ( c) Animals Plants.

(a) what is the rate at which energy being delivered to a light bulb higher : just after it is turned on , the glow of the filament is increasing , or after it has been on for a few seconds and the glow is steady ? (b) IF a piece of wire is used to connect points b and c in Fig. 7.9, does the brightness of bulb R_(1) increase , decrease or stay constant ? What happens to the brightness of bulb R_(2) ? (I_(1) = I_(2) = I) (c) Compare the brightness of four identical light bulbs in Fig. 7.10 . What happens if the bulb A fails so that it cannot conduct ? What if C fails ? What if D fails? (d) If electric power is transmitted over long distances, the resistance of the wires becomes significant. Why ? Which mode of transmission would result in less energy losss: high current and low voltage or low current and high voltage ? Discuss. (e) In Fig. 7.11 , describe wha happens to the light bulb after the switch is closed . Assume the capacitor has a large capacitance and is initially uncharged. (f) Astuident claims that a second light bulb in series is less bright than the first , because the first bulb uses up some of the current . How would you respond to this statement ? (g) If you were to design an electeric heater using nichrome wire as the heating element , what parameters of the wire would you vary to meet a specific power output , sch as 1000 W ?

(a) what is the rate at which energy being delivered to a light bulb higher : just after it is turned on , the glow of the filament is increasing , or after it has been on for a few seconds and the glow is steady ? (b) IF a piece of wire is used to connect points b and c in Fig. 7.9, does the brightness of bulb R_(1) increase , decrease or stay constant ? What happens to the brightness of bulb R_(2) ? (I_(1) = I_(2) = I) (c) Compare the brightness of four identical light bulbs in Fig. 7.10 . What happens if the bulb A fails so that it cannot conduct ? What if C fails ? What if D fails? (d) If electric power is transmitted over long distances, the resistance of the wires becomes significant. Why ? Which mode of transmission would result in less energy losss: high current and low voltage or low current and high voltage ? Discuss. (e) In Fig. 7.11 , describe wha happens to the light bulb after the switch is closed . Assume the capacitor has a large capacitance and is initially uncharged. (f) Astuident claims that a second light bulb in series is less bright than the first , because the first bulb uses up some of the current . How would you respond to this statement ? (g) If you were to design an electeric heater using nichrome wire as the heating element , what parameters of the wire would you vary to meet a specific power output , sch as 1000 W ?

To a block of wood, a metal sphere is attached with the help of a string and the whole arrangement is dropped in a water container as shown in the figure. If the wooden block floats in water, then which of the following statements is true? (a) Upthrust on the wooden block is equal to its weight. (b) Upthrut on the metal sphere is equal to its weight. (c) Tension in the string is equal to its weight. of metal sphere. (d) Tension in the string is less than the weight of metal sphere.

A crystalline solid (A) reacts with hydrogen gas to form a monoatomic gas (B) and a highly associated liquid ( C).(A) is soluble in water and undergoes hydroloysis slowly to form (B),(C ) and a diatomic gas (D).When pure and dry (D) is subjected to a silent electric discharge an another pale blue gas (E) is produced which like (A) also acts a strong oxidising agent.(E) dissolves in potassium hydroxide forming an orange coloured solid which is paramagnetic in nature. (A) reacts with IF_5, SbF_5, PF_5 etc to form the addition compounds. (C ) forms an addition compound (F) with KF with when electrolysed in molten state forms a most reactive gas (G).(B) and (G) (taken in 2:1) ratio when heated in nickel tube at 400^@ C and 6 atm pressure forms (A).The first ionization energy (IE_1) of (B) is fairly close to (D). Which of the correct choice for (D) and (E) ?