Chemistry MCQs

Notes:
The most important form of elemental phosphorus from the perspective of applications and chemical literature is white phosphorus. It consists of tetrahedral P4 molecules, in which each atom is bound to the other three atoms by a single bond. This P4 tetrahedron is also present in liquid and gaseous phosphorus up to the temperature of 800 °C when it starts decomposing to P2 molecules

Notes:
Nitrolim is a type of fertilizer that was widely used in the past. The main components of Nitrolim are calcium carbide and nitrogen. Calcium carbide reacts with nitrogen to form calcium cyanamide, which is an active ingredient in Nitrolim. This fertilizer is significant as it helps in fixing nitrogen in the soil thereby promoting plant growth.

Notes:
Transuranic elements are those with atomic numbers greater than 92, which is the atomic number of uranium. These elements, including plutonium (94) and americium (95), are all synthetic and typically unstable, often used in nuclear applications and research. The term “transuranic” specifically refers to elements beyond uranium in the periodic table.

Notes:
Sodium bicarbonate, commonly known as baking soda, is used in baking due to its ability to decompose above 70 degrees Celsius and release carbon dioxide. This chemical reaction is given by the equation 2 NaHCO3 – Na2CO3 + H2O + CO2. In baking, it reacts with other ingredients or decomposes at high temperatures to produce carbon dioxide, which causes the dough to rise, creating the fluffy texture in baked goods.

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The first ionization enthalpy of these metals is higher than corresponding Group 1 metals due to the small size of these elements compared to the corresponding alkali metals. The second ionization enthalpy of these metals is lower than corresponding alkali metals.

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Carnetite is an ore of Uranium, where as Sphalerite(Zinc blende), Zincite and Calamine are some of the important ores of Zinc.

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Greenocite is an important ore of Cadmium. Ruby Silver is an important ore of Silver. Silestine is an ore of Strontium and Salt peter is an ore of Potassium.

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A reaction in which a single product is formed from two or more reactants is known as a combination reaction. For example: calcium oxide and water combine to form a single product, slaked lime or calcium hydroxide.

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The effective nuclear charge of an element increases as we move from left to right in the periodic table.

Notes:
A solute or substance which completely ionize or dissociates in a solution is called as strong electrolyte. The ions of strong electrolytes are good conductors of electricity in the solution. For example, HCl, HBr, HI, HNO3, NaOH, KOH, etc.