CBSE 11TH CHEMISTRY - Online Test
Q1. The number of position isomers of is
Answer : Option A
Explaination / Solution:
n-pentyne , 3-methyl butyne, pent-2-yne
Q2. The strength of a reductant/oxidant in redox systems can be determined
Answer : Option C
Explaination / Solution:
Because a redox indicator (also called an oxidation-reduction indicator) is an indicator which undergoes a definite color change at a specific electrode potential.
Q3. In the case of compounds such as etc which of the following term is used as bond enthalpy.
Answer : Option D
Explaination / Solution:
For polyatomic molecules the term mean bond enthalpy is used for the enthalpy changes associated with chemical bonds.
Q4. s-block elements comprise of
Answer : Option A
Explaination / Solution:
s-block contains two group of elements including alkali earth metal and alkaline earth metal.
Q5. According to quantum theoretical model of an atom each orbital is designated by three quantum numbers labelled as n, l and ml. These are referred to respectively as
Answer : Option B
Explaination / Solution:
Quantum numbers designate specific shells, subshells, orbitals, and spins of electrons. This means that they describe completely the characteristics of an electron in an atom, i.e., they describe each unique solution to the Schrödinger equation, or the wave function, of electrons in an atom.
There are a total of four quantum numbers: the principal quantum number (n), the orbital angular momentum quantum number (l), the magnetic quantum number (ml), and the electron spin quantum number (ms). The principal quantum number, nn , describes the energy of an electron and the most probable distance of the electron from the nucleus. In other words, it refers to the size of the orbital and the energy level an electron is placed in. The number of subshells, or ll , describes the shape of the orbital. It can also be used to determine the number of angular nodes.
The magnetic quantum number, ml, describes the energy levels in a subshell, and ms refers to the spin on the electron, which can either be up or down.
Q6. Deforestation and burning of fossil fuels adds to the environmental pollution by :
Answer : Option C
Explaination / Solution:
Deforestation and burning of fossil fuels adds to the environmental pollution As it increases the amount of CO2 in the atmosphere which traps excessive heat and increases global temperature causing global warming.
Q7. Molecular formula represents
Answer : Option D
Explaination / Solution:
Molecular formula is the exact no. of atoms present in a molecule of a compound.
Molecular formula of a compound is related with its empirical formula as ,
Mollecular formula = ( Empirical formula ) n
where n represents a positive integer .
Q8. Many d-block and f-block elements form
Answer : Option B
Explaination / Solution:
Hydrides are formed by many d-block and f-block elements when heated with hydrogen under pressure. The hydrides tend to be non-stoichiometric and they may be of variable composition.These hydrides have properties similar to those of parent metal and hence are known as metallic hydride.
Q9. the valence shell electron pair repulsion (vsepr) theory helps in the
Answer : Option A
Explaination / Solution:
Valence shell electron pair repulsion (VSEPR) theory is a model used in chemistry to predict the geometry of individual molecules from the number of electron pairs surrounding their central atoms. It is also named the Gillespie-Nyholm theory after its two main developers.
Q10.
The molecular formula represents two alcohols: propan-1-ol and propan-2-ol. This property is called as:
Answer : Option D
Explaination / Solution:
propan-1-ol and propan-2-ol are positional isomers as they differ only in the position of functional group -OH.
Positional isomers are isomers that have the same carbon skeleton and the same functional groups but differ from each other in the location of the functional groups on or in the carbon chain.
