Metal + Oxygen → Metallic oxide Non-metals do not displace hydrogen from dilute acids.
How are metals such as copper, zinc, tin, nickel, silver, gold etc., obtained in metallurgical operations refined? Lead displaces hydrogen from dilute mineral acids very slowly. The existence of a chemical element in more than one form with various forms having different physical properties but similar chemical properties is known as allotropy. Impurities like sand, rock etc., which are present in an ore, are known as gangue materials. Reaction shown in 3 is possible because Zn is more reactive than Fe.
Platinum, sold and silver are used to make jewellery. are moderately reactive. 2. Classify the following into metals and non-metals: mercury, gold, calcium, bromine, oxygen, sodium, sulphur and magnesium. Answer: It is observed that a chemical reaction has taken place in the test tube in which iron nail was dipped in copper sulphate solution. oxides. Aluminium (s) + Oxygen (g) → Aluminium oxide (s) The two substances essential for rusting of iron are oxygen (air) and water. It has just one electron in its valence shell. The ability of metals to be drawn into thin wires is known as Answer: Question 158. Question 149. Two metals that are found in nature in free state are platinum and gold. Most metals react with and burn in air at various temperatures forming their respective metallic During electrolytic refining of zinc, pure metal Aluminium on heating over a flame burns in oxygen with a white flame to form aluminium oxide. Question 82. Answer: A sample of an ore is heated in a test tube. Answer: Question 155. Electron-dot structure is based on the concept of the octet rule in which atoms share electrons so that each atom has 8 electrons in its outermost shell.
Generally non-metals are not lustrous. Place 2-3 cleaned iron nails in each of the test tubes. Which of the following pairs will give displacement reactions? Name the gaseous products obtained by the electrolysis of aqueous sodium chloride solution. The person who was posing as goldsmith must have used Aqua regia. Mercury (Hg) is a metal of low reactivity. Therefore, these metals cannot be kept in the open as air also contains moisture. The lady was upset but after a futile argument the man beat a hasty retreat. Thermit reactions are used: Question 135. The reaction of iron (III) oxide (Fe2O3) with aluminium is used to join railway tracks or to join cracked machine parts. Nuclear Magnetic Resonance (NMR) has been around since 1938 and has benefited the field of chemistry and medicine in important ways, helping researchers and chemist to identify and measure certain elements found on the periodic table. What is galvanisation? List the characteristics of thermit process. They react so vigorously with oxygen that they catch fire if kept in the open. Answer: Answer: Question 103.
Answer: Question 152. Metals usually give a characteristic resonant ringing sound when hit by another object. All chemical compounds have chemical elements in a fixed composition. Place the metal to be tested in the circuit between terminals A and B connecting the two terminals. Question 46. What's the deal with chlorine you say? An unsuspecting lady save a set of sold bangles to him, which he dipped in a particular solution. In the electrolytic refinine of a metal M, what would you take as the anode, the cathode and the electrolyte? It is observed that similar result is seen with most metals. Explain with an example.
Gangue: It is a sulphide ore. In electrolytic refining, impure metal is made as anode Question 145. Magnesium bums brilliantly producing a bright flame. First, the ore is concentrated by a suitable process. On further heating, a gas is evolved which makes a glowing splinter burn brilliantly. Answer: Iron objects can be protected from rusting by coating their surface with rust-proof paints. Scientific Gear is a manufacturer and distributor of scientific laboratory equipment. why? Hence, sodium chloride (NaCl) is known as an Ionic Compound. Metals are generally malleable. Iron nail kept in a closed jar containing calcium chloride does not rust. (A) chromium Heat the rod with a spirit lamp from the opposite end. Save my name, email, and website in this browser for the next time I comment. Iron combines with oxygen in presence of water vapour to form a hydrated oxide of iron called rust. Answer: Naturally occurring compounds of elements found in the earth’s crust are known as minerals.
3. Question 153. Electron-dot structure of sodium, oxygen and magnesium: 2. Answer: Which one of the following metals would be displaced from the solution of its salts by the other three metals? The process of extracting metals from their ores and subsequently refining them is called metallurgy. What happens when metals are burnt in air? Two metals that can form stable hydrides with hydrogen are sodium and calcium. In metallurgy, heating a sulphide ore in presence of air (oxygen) is called roasting. Nitric acid itself gets reduced to any of the nitrogen oxides (N2O, NO, or NO2). This establishes that different metals differ in their reactivities. Question 96.
Which of them can form anion? Give reason. Take small pieces of easily available metals. Oxides that react with both acids and bases to form salt and water are known as amphoteric oxides.
Compounds that contain ions and are held together by ionic bonds are called ionic compounds. The concentrated ore is heated strongly in limited supply of air. Answer: Metals such as copper, silver, lead and gold do not react with water. Reaction of aluminium oxide with sodium hydroxide: The arrangement or distribution of electrons in the various shells and orbitals of an atom is called its electronic configuration. The element is likely to be
This method for measuring salt is more involved, takes a little more time (3 to 6 minutes usually), but is very accurate to the parts per million (PPM) level. The ions present in sodium oxide are Na+ and O2- (also written as O
(B) Sodium
Iron is more reactive than lead and lead is more reactive than copper. (C) Magnesium Question 75. The results obtained have been tabulated as follows: Which of the following non-metals is lustrous? An element A is soft and can be cut with a knife. Ionic compounds are formed by the chemical union of positive and negative ions. Question 139. will give hydrogen gas with dilute nitric acid. However, all metals do not react with acids.
Concentrated nitric acid (HNO3) is a strong oxidising agent. Iron reacts with oxygen and rusts only in presence of moisture or water. But ore is a chosen mineral of a metal, from which metal is extracted profitably on a large scale, in pure form. They do not react with oxygen even at high temperatures. How do you say that different metals have different reactivities? Answer: Explain with an example how a metal of low reactivity is extracted from its ore. Where are these metals placed in the reactivity series? (D) Metals displace hydrogen gas from dilute acids. What are the ions present in these compounds? Question 43. Question 127. A non-metal that exists in liquid state at room temperature is bromine. This means oxides of metals are basic in nature. Metals are chemical elements that are opaque, ductile, lustrous and are good conductors of heat and electricity.
Two well-known allotropes of carbon are diamond and graphite. Salt Testing Question 26. Question 25. Al2O3 + 6 HCl → 2 AlCl3 + 3 H2O, 2. Minerals are chemical compounds that are widely distributed in the earth’s crust in the form of carbonates, oxides, sulphates, sulphides, nitrates, etc. Give reasons for the following: Answer: Answer: Question 93. Answer: Question 24. HNO3 to make royal water called aqua regia.