Combined package (eBooks) of Solved Guess Papers for Class 12 Mathematics, Physics and Chemistry is available here. This package is specially prepared for the students who are going to appear for CBSE Class 12th board exam 2018. This package is important for practice as well as revision.
Solved Guess Papers for CBSE board exam 2018 are available here. These guess papers are available in the form of a combined package. This package is specially prepared for Maths and Science students who are going to appear for CBSE board exam 2018.
CBSE has recently released Class 12 date sheet. As per the date sheet, CBSE Class 12 board exams, 2018 will start from 5 March 2018 (English paper). Now, students don’t have much time for preparation. This is the time when students need to focus more on revision & practice rather than studying new topics.
Due to this reason, Jagranjosh.com has provided a complete package for the Class 12th students having Mathematics, Chemistry and Physics subjects. These papers are developed by subject experts after the brief analysis of previous 5 years’ papers.
After going through previous year papers, our subject experts learned that questions based on some important concepts are frequently asked in CBSE board exams, every year. These solved guess papers contain all such important concepts. These guess papers are also based on latest examination pattern. This package will be very helpful for the students preparing for CBSE board exam 2018.
The presence of nitro group at ortho- and para-positions withdraws the electron density from the benzene ring and thus facilitates the attack of the nucleophile on haloarene. The carbanion thus formed is stabilised through resonance. The negative charge appeared at ortho- and para- positions with respect to the halogen substituent is stabilised by –NO2 group while in case of meta-nitrobenzene, none of the resonating structures bear the negative charge on carbon atom bearing the –NO2 group. So, the presence of nitro group at meta- position does not stabilise the negative charge and no effect on reactivity is observed by the presence of –NO2 group at meta position.
(a) Emulsion: It is a colloidal dispersion in which both the dispersed phase and the dispersion medium are liquids.
(b) Tyndall Effect: It is defined as the scattering of light by the colloidal particles present in colloidal solution.
(c) Autocatalysis: It is reaction in which one of the product acts as a catalyst then, it is called autocatalysis.
(i) Nickel does not form low spin octahedral complexes.
(ii) The p-complexes are known for the transition metals only.
(iii) Co2+ is easily oxidised to Co3+ in the presence of a strong ligand.
(i) Nickel does not form low spin octahedral complexes because ‘Ni’ has electronic configuration 3d8 4s2, in which two inner d-orbitals are not available which are required to form d2sp3hybridization.
(ii) The p-complexes are known for the transition metals only because they have ‘sandwich’ structure in which the metal ion lies between two planar C5H5 rings. The bonding involves overlap of p-electrons of the C5H5 rings with unfilled d-orbital of the metal. So, that all M–C bonds are identical for their stability.
(iii) Co2+ is easily oxidised to Co3+ in the presence of a strong ligand because in presence of strong ligand, the 3d electrons pair up leaving two orbitals empty to be involved in d2sp3 hybridisation.