Chemistry Test - 22

We know,
$∆H=∆U+∆nRT$
$∆n=$ [Total number of moles of gaseous products]-[Total number of moles of gaseous reactants]
For this reaction
$A\left(s\right)+3B\left(\mathrm{g}\right)\to 4C\left(\mathrm{g}\right)+D\left(l\right)$
$∆n=\left[4-3\right]$
=1
$∆H=∆U+RT$

The decreasing order of boiling point is

This is because of hydrogen bonding and vanderwaals force of attractions.

Main Concept :
Smelting-carbon reduction process & Slag formation with fluxes Smelting : The process of extracting a metal in the state of fusion is called smelting. In this process the ore is mixed with carbon, obtained after the above reactions and heated in suitable furnace. A suitable flux is added during the operation to convert the non–fusible gangue to fusible slag. The metallic oxide is reduced by carbon and the metal may be obtained in the molten state or as vapours which are condensed. Metals like tin, zinc or lead are obtained by this process.

Flux and slag : Flux is a substance that is added during smelting to convert infusible silicons or earthy impurities into fusible material known as slag. Impurities + Flux = Slag. The slag is immiscible with the metal and has a low melting point and density. The slag floats on the metal and protects it from oxidation. It is removed from the furnace through the slag hole. If the impurities in the ore are acidic (SiO₂) in nature, a basic flux e.g., CaO, MgO, FeO etc. are added; and if the impurities are basic (CaO, FeO, etc.) then on acidic flux (SiO₂) is used. The gangue or matrix present in the ore is refractory or non–fusible in nature but it reacts with the flux forming fusible slag which does not mix with the molten metal and forms the upper layer. Slag are usually silicates.

Due to intermolecular hydrogen bonding, alcohols are less volatile than ether

Presence of electron withdrawing group such as ${\mathrm{NO}}_2,\mathrm{CHO}$ etc, on benzene nucleus, makes phenol more acidic by stabilising phenoxide ion while presence of electron releasing groups such as $-{\mathrm{CH}}_3-{\mathrm{C}}_2{\mathrm{H}}_5$ destabilises the phenoxide ion, thus makes the phenol less acidic. Hence, the order of acidity of given compound is

All molecules have same hybridisation i.e sp³d and have similar structure, the T-shaped. So,they are isostructural

${\mathrm{CH}}_2=\mathrm{CH}-\mathrm{CH}={\mathrm{CH}}_2(1,3-\text{ dibutene })$ is a conjugate diene because it has alternate carbon-carbon single and double bonds. It reacts with HBr. It also polymerises to form Buna-N rubber etc.