19,000+ solved questions for JEE Advanced, JEE Mains, NEET & IChO — with answers and expert explanations.
Thermite a mixture used for welding is:
The reaction which is not involved in thermite process: (a) 3Mn O 8Al 9Mn 4Al O + ¾¾® + (b) Cr O 2Al 2Cr Al O + ¾¾® + (c) 2Fe Al O Fe O 2Al + ¾¾® + (d) B O 2Al 2B Al O + ¾¾® +
Anodising can be done by electrolysing dilute H2SO4 with aluminium as anode. This results in :
Assertion : PbI4 is a stable compound. Reason : Iodide stabilizes higher oxidation state.
Assertion : SiF - is known but SiCl - is not. Reason : Size of fluorine is small and its lone pair of electrons interacts with d-orbitals of Si strongly.
Assertion : Between SiCl4 and CCl4, only SiCl4 reacts with water. Reason : SiCl4 is ionic and CCl4 is covalent.
Assertion : Pb4+ compounds are stronger oxidising agents than Sn2+ compounds. Reason : The higher oxidation states for the group 14 elements are more stable for the heavier members of the group due to ‘inert pair effe…
Assertion : In water, orthoboric acid behaves as a weak monobasic acid. Reason : In water, orthoboric acid acts as a proton donor.
Assertion : Boron is p block element. Reason : Last electron entres in p sub shell.
Assertion : Boron always forms covalent bond. Reason : The small size of B3+ favours formation of co- valent bond.
Assertion : AlF3 is soluble in KF but addition of BF3 brings its precipitation. Reason BF3 is more acidic than AlF3.
Assertion : BF3 is a weaker Lewis acid than BCl3. Reason : BF3 molecule is stabilized to a greater extent than BCl3 by B—F p-bonding.
Assertion : Al(OH)3 is amphoteric in nature. Reason : Al—O and O—H bonds can be broken with equal ease in Al (OH)3.
Match the column I with column II and mark the appropriate choice. Column I Column II (A) Galena (i) Abrasive (B) Diamond (ii) Metal carbonyls (C) Carbon monoxide (iii) Hydrides of Si (D) Silanes (iv) An ore of lead
Which of the following is not matched correctly with its use ?
When an inorganic compound (X) having 3C—2e as well as 2c—2e bonds reacts with ammonia gas at a cer- tain temperature, gives a compound (Y), isostructural with benzene. Compound (X) with ammonia at a high temperature …
A metal X reacts with aqueous NaOH solution to form Y and a highly inflammable gas. Solution Y is heated and CO2 is poured through it. Z precipitates out and Na2CO3 is formed. Z on heating gives Al2O3, Identify X, Y a…
The blue coloured mineral ‘Lapis Lazuli’ which is used as a semi-precious stone is a mineral of the following class:
Assertion: Coloured cations can be identified by borax bead test. Reason: Transparent bead (NaBO2 + B2O3) forms coloured bead with coloured cation. (AIIMS 2009)
Product of the following reaction is Al C D O -> (PMT 2008)
White lead is (CPMT 2007)
Supercritical CO2 is used as (AIIMS 2007)
Litharge is chemically (AIIMS 2007)
For which one of the following minerals, the composition given is incorrect? (Kerala CEE 2007)
In borax bead test which compound is formed? (Punjab PMET 2007)