Maharashtra State Board
- Write chemical equation for the following events. Iron filings are dropped in aqueous solution of copper sulphate iron is more reactive than copper. it is displacement reaction in which iron displace copper sulphate in the reaction. colour of the solutio... 1
- Write chemical equation for the following events. Aluminium came in contact with air. Aluminum is a very reactive metal. The outer surface of the metal is actually covered by a very thin layer of the oxide which keeps the meta... 1
- Draw a neat labelled diagram Hydraulic separation method. labelled diagram 1
- Draw a neat labelled diagram Electrolytic reduction of alumina. labelled diagram 1
- Draw a neat labelled diagram Froth floatation method. labelled diagram 1
- Draw a neat labelled diagram Magnetic separation method labelled diagram 1
- The electronic configuration of metal ‘A’ is 2,8,1 and that of metal ‘B’ is 2,8,2. 1) moving from left to right in a period of periodic table, the chemical reactivity of elements first decreases from sodium to silicon and t... 2
- When a copper coin is dipped in silver nitrate solution, a glitter appears on the coin after some time. Copper is more reactive than silver. Hence displacement reaction occurs. When copper coin is dipped in silver nitrate solution forming coppe... 1
- Anodes need to be replaced from time to time during the electrolysis of alumina. Anodes needs to be replaced during the electrolysis of the Alumina because they gets oxidized. During the Electrolysis of the Alumina, Oxyge... 1
- Pine oil is used in froth flotation. Answer: Pine oil is used in froth flotation because the ore particles are preferentially wetted by oil, while the gangue (impurities) is wet... 1
- Sodium is always kept in kerosene. Sodium are very reactive metals and kept in kerosene oil to prevent it from coming in contact with oxygen and moisture as they react to form... 1
- Generally the ionic compounds have high melting points. Ionic compounds are mostly solids and are packed in a crystal lattice structure . They have strong electrovalent bonds between the constitue... 1
- Lemon or tamarind is used for cleaning copper vessels turned greenish. Copper reacts with carbon dioxide in the air to form copper carbonate. As a result, copper loses its shiny brown surface forming a green lay... 1
- Explain the term Gangue The impurities present in the one such as sand , rocks etc are known as gangue. 2
- Explain the term Minerals The compounds of metals that occur in nature along with the impurities are called minerals. minerals are the natural source in which the met... 1
- Explain the term Ores metals are commercially extracted from minerals at low cost and minimum efforts .These minerals are called ores. ores are raw materials for... 1
- Metallurgy Explain the terms. Metallurgy defined as extraction of metal from their pure form. metals are commercially extracted from minerals at low cost and minimum effo... 2
- Identify the pairs of metals and their ores from the following. Group A. Group B A. Bauxite. 1. Aluminium B. Cassiterite. 2.Tin c. Cinnabar. 3. Mercury 1
- Make pairs of substances and their properties Substance. Property A. Potassium bromide. 1.Combustible Substance. Property A.Potassium bromide 1. Soluble in water b. Gold. 2. High ductility. C.Sulphur. 3. Combustible. D. Neon. 4. No chemical r... 1
- Write names. a. Alloy of sodium with mercury. b. Molecular formula of the common ore of aluminum. a. Alloy of sodium with mercury. Answer:: Sodium amalgam, commonly denoted Na(Hg), is an alloy of mercury and sodium. b. Molecular formula o... 1
- An object kept 60 cm from a lens gives a virtual image 20 cm in front of the lens. Answer: focal length = −30 cm; it is a diverging (concave) lens. Using the Cartesian sign convention, the object is on the left: u = -60 cm.... 1
- Three lenses having power 2, 2.5 and 1.7 D are kept touching in a row. What is the total power of the lens combination? Answer: 6.2 D When thin lenses are kept in contact, the power of the combination is the sum of their individual powers: P = P₁ + P₂ + P₃ = 2... 1
- 5 cm high object is placed at a distance of 25 cm from a converging lens of focal length of 10 cm. Answer: the image is 16.7 cm behind the lens, 3.33 cm tall, real, inverted and diminished. Using the Cartesian sign convention: u = -25 cm,... 1
- Doctor has prescribed a lens having power +1.5 D. What will be the focal length of the lens? What is the type of the lens and what must be the defect of vision? Given: Power of lens, P = +1.5 D, f=? Now, focal length of lens, f=1/P =1/(+1.5D) =10/15 m =+0.67 m P is positive, This shows the lens is co... 1