The Class 10 is an important year in a student’s life and Maharashtra State Board Science 1 is one of the subjects that require dedication, hard work, and practice. It’s a subject where you can score well if you are well-versed with the concepts, remember the important formulas and solving methods, and have done an ample amount of practice. Worry not! Home Revise is here to make your Class 10 journey even easier. It’s essential for students to have the right study material and notes to prepare for their board examinations, and through Home Revise, you can cover all the fundamental topics in the subject and the complete Maharashtra State Board Class 10 Science 1 Book syllabus.
1. Explain the terms.
a. Metallurgy
b. Gangue
Answer: Metallurgy is the science and technology regarding the extraction of metals from ores and their purification for the use. Ores are the minerals from which the metal can be separated economically. In the meanwhile, ores contain several types of impurities such as soil, sand and rocky substances along with the metal compounds. These impurities are known as gangue. Now, metals can be extracted from their ores using various methods of separation. The process of extraction of metal in a pure state from the ores is also a part of metallurgy.
2. Give a scientific reason for why lemon or tamarind is used for cleaning copper vessels that turned greenish.
Answer: Copper vessels turn greenish when they react with the carbon dioxide in the air to form copper carbonate. Hence, copper vessels lose the shiny brown surface. Now, the citric acid found in the lemon or tamarind, neutralizes the basic copper carbonate, thus dissolving the layer. This is the reason why tarnished copper vessels cleaned with lemon or tamarind helps the copper vessels to retain their lustre.
3. The electronic configuration of metal ‘A’ is 2,8,1 and that of metal ‘B’ is 2,8,2. Which of the two metals is more reactive? Write their reaction with dilute hydrochloric acid.
Answer: While moving from left to right in a periodic table, the chemical reactivity of the elements decreases from sodium to silicon and then it increases from phosphorus to chlorine. Electronic configuration of metal A is given as 2,8,1, (same as the electronic configuration for sodium metal) while that of metal B is 2,8,2 (the electronic configuration of magnesium metal). Meanwhile, the first element of the third period, sodium has 1 valence electron, which it can lose easily to react with other substances. For this reason, sodium is a highly reactive metal. The second element, magnesium has 2 valence electrons, which is not so easy to lose. For this reason, magnesium is less reactive than sodium.
Reactions with dilute hydrochloric acid:
Na + HCl → NaCl + H2
Mg + HCl → MgCl2 + H2
4. What is sonorous metals?
Answer: Sonority is a sound produced when certain metals are struck. These metals are known as sonorous metals.
5. What are the physical properties of non-metals?
Answer: Some non-metals exist in solid state while some are in gaseous state. However, bromine is the non-metal, which is an exception as it is found in liquid state. Non-metals except iodine, which is shiny do not have lustre. Non-metals are not hard. However, the allotrope diamond is the hardest natural substance. Meanwhile, the melting and boiling points are low for non-metals. They are also bad conductors of electricity and heat. But, Graphite, an allotrope of carbon, an exception is a good conductor of electricity.
6. What is Aqua Regia?
Answer: A highly corrosive and fuming liquid used as one of the few reagents that can dissolve the noble metals like gold and platinum is called Aqua Regia. It is freshly prepared by mixing concentrated hydrochloric acid and concentrated nitric acid in the ratio of 3:1.
7. What are the general properties of ionic compounds?
Answer: These are the general properties of ionic compounds:
1. Since the attractive force between the positively and negatively charged ions is strong, the ionic compounds can be found in solid state and are hard.
2. On applying pressure, the ionic compounds can be broken into pieces as they are brittle.
3. The intermolecular force of attraction is high in ionic compounds and a large energy is required to overcome it. For this reason, ionic compounds have high melting and boiling points.
4. Ionic compounds are soluble in water because the water molecules orient in a particular manner around the ions separated by the dissociation process. Because of this, a new force of attraction is established between the ion and the surrounding water molecules. This replaces the original intermolecular attraction; and aqueous solutions of ionic compounds are formed. Ionic compounds are however, insoluble in solvents like kerosene and petrol. This is because unlike water a new attractive force can not be established in these solvents.
5. In solid state, the ionic compounds cannot conduct electricity and the ions cannot leave their places. However, in their fuse/ molten state ionic compounds can conduct electricity, because in this state they contain the dissociated ions. On passing current through the solution the ions move towards the oppositely charged electrodes. Because of the electrical conductivity in fused and dissolved state the ionic compounds are called electrolytes.
8. What is concentration of ores?
Answer: Concentration of ores is the process of separating gangue from the ores. In this the concentration of the compound of the desired metal is increased via various ways. However, the exact way to be used depends upon the physical properties of the metal present in the ores and the gangue as well as the reactivity of the metal and the facilities available for the purification.
9. What is the froth floatation method?
Answer: The froth floatation method is based on the two opposite properties, hydrophilic and hydrophobic, of the particles. The particles of the metal sulphides, due to their hydrophobic property, get wetted mainly with oil, while due to the hydrophilic property the gangue particles get wetted with water. By applying these properties certain ores are also concentrated using the froth floatation method. In this method the finely ground ore is put into a big tank containing ample amount of water. Certain vegetable oil such as pine oil eucalyptus oil, is added in the water to form the froth. Pressurised air is blown through the water. There is an agitator rotating around its axis in the centre of the floatation tank. The agitator is used as per the requirement. Bubbles are formed due to the blown air. A foam is formed from oil, water and air bubbles together, due to the agitation, which rises to the surface of water and floats. That is why this method is called the froth floatation process. Particles of certain sulphide ore float with the foam on water as they preferentially get wetted by the oil. For example, this method is used for the concentration of zinc blend (ZnS) and copper pyrite (CuFeS2 ).
10. Which are more reactive metals?
Answer: The metals found at the top of the reactivity series are highly reactive. As you go down the series, their reactivity decreases. Examples for reactive metals are potassium, sodium, aluminium. Reactive metals lose electrons in the outermost shell and have large capacity to form cations. For example, reactive metals react vigorously with dilute acids to give hydrogen gas. Highly reactive metals burn by reacting with oxygen from air at room temperature. They can only be extracted by electrolytic reduction.