Write the important conditions required for the linear combination of atomic orbitals to form molecular orbitals.
Question: Write the important conditions required for the linear combination of atomicorbitals to form molecular orbitals. Solution: The given conditions should be satisfied by atomic orbitals to form molecular orbitals: (a) The combining atomic orbitals must have the same or nearly the same energy. This means that in a homonuclear molecule, the 1s-atomic orbital of an atom can combine with the 1s-atomic orbital of another atom, and not with the 2s-orbital. (b) The combining atomic orbitals must...
Read More →Why do we call our heart myogenic?
Question: Why do we call our heart myogenic? Solution: Inthe human heart, contraction is initiated by a special modified heart muscle known as sinoatrial node. It is located in the right atrium. The SA node has the inherent power of generating a wave of contraction and controlling the heart beat. Hence, it is known as the pacemaker. Since the heart beat is initiated by the SA node and the impulse of contraction originates in the heart itself, the human heart is termed myogenic. The hearts of ver...
Read More →Explain the formation of H2 molecule on the basis of valence bond theory.
Question: Explain the formation of H2molecule on the basis of valence bond theory. Solution: Let us assume that two hydrogen atoms (A and B) with nuclei (NAand NB) and electrons (eAand eB) are taken to undergo a reaction to form a hydrogen molecule. When A and B are at a large distance, there is no interaction between them. As they begin to approach each other, the attractive and repulsive forces start operating. Attractive force arises between: (a) Nucleus of one atom and its own electron i.e.,...
Read More →Describe the evolutionary change in the pattern of heart among the vertebrates.
Question: Describe the evolutionary change in the pattern of heart among the vertebrates. Solution: All vertebrates possess a heart a hollow muscular organ composed of cardiac muscle fibres. The function of the heart is to pump oxygen to all parts of the body. The evolution of the heart is based on the separation of oxygenated blood from deoxygenated blood for efficient oxygen transport. In fishes, the heart was like a hollow tube. This evolved into the four-chambered heart in mammals. Piscean h...
Read More →Distinguish between a sigma and a pi bond.
Question: Distinguish between a sigma and a pi bond. Solution: The following are the differences between sigma and pi-bonds:...
Read More →What do you understand by bond pairs and lone pairs of electrons?
Question: What do you understand by bond pairs and lone pairs of electrons? Illustrate by giving one example of each type. Solution: When two atoms combine by sharing their one or more valence electrons, a covalent bond is formed between them. The shared pairs of electrons present between the bonded atoms are calledbond pairs. All valence electrons may not participate in bonding. The electron pairs that do not participate in bonding are calledlone pairsof electrons. For example, in C2H6(ethane),...
Read More →Which hybrid orbitals are used by carbon atoms in the following molecules?
Question: Which hybrid orbitals are used by carbon atoms in the following molecules? (a) CH3CH3; (b) CH3CH=CH2; (c) CH3-CH2-OH; (d) CH3-CHO (e) CH3COOH Solution: Both C1and C2aresp3hybridized. C1issp3hybridized, while C2and C3aresp2hybridized. Both C1and C2aresp3hybridized. C1issp3hybridized and C2issp2hybridized. C1issp3hybridized and C2issp2hybridized....
Read More →Describe the evolutionary change in the pattern of heart among the vertebrates.
Question: Describe the evolutionary change in the pattern of heart among the vertebrates. Solution: All vertebrates possess a heart a hollow muscular organ composed of cardiac muscle fibres. The function of the heart is to pump oxygen to all parts of the body. The evolution of the heart is based on the separation of oxygenated blood from deoxygenated blood for efficient oxygen transport. In fishes, the heart was like a hollow tube. This evolved into the four-chambered heart in mammals. Piscean h...
Read More →Write the differences between:
Question: Write the differences between: (a) Blood and Lymph (b) Open and Closed system of circulation (c) Systole and Diastole (d) P-wave and T-wave Solution:...
Read More →Considering x-axis as the internuclear axis which out of the following will not form a sigma bond and why?
Question: Considering x-axis as the internuclear axis which out of the following will notform a sigma bond and why? (a) 1sand 1s (b) 1sand 2px (c) 2pyand 2py (d) 1sand 2s. Solution: 2pyand 2pyorbitals will not a form a sigma bond. Takingx-axis as the internuclear axis, 2pyand 2pyorbitals will undergo lateral overlapping, thereby forming a pi () bond....
Read More →What is the total number of sigma and pi bonds in the following molecules?
Question: What is the total number of sigma and pi bonds in the following molecules? (a) C2H2 (b) C2H4 Solution: A single bond is a result of the axial overlap of bonding orbitals. Hence, it contributes a sigma bond. A multiple bond (double or triple bond) is always formed as a result of the sidewise overlap of orbitals. A pi-bond is always present in it. A triple bond is a combination of two pi-bonds and one sigma bond. Structure of C2H2can be represented as: Hence, there are three sigma and tw...
Read More →What is the total number of sigma and pi bonds in the following molecules?
Question: What is the total number of sigma and pi bonds in the following molecules? (a) C2H2 (b) C2H4 Solution: A single bond is a result of the axial overlap of bonding orbitals. Hence, it contributes a sigma bond. A multiple bond (double or triple bond) is always formed as a result of the sidewise overlap of orbitals. A pi-bond is always present in it. A triple bond is a combination of two pi-bonds and one sigma bond. Structure of C2H2can be represented as: Hence, there are three sigma and tw...
Read More →What is meant by double circulation? What is its significance?
Question: What is meant by double circulation? What is its significance? Solution: Double circulation is a processduring which blood passes twice through the heart during one complete cycle. This type of circulation is found in amphibians, reptiles, birds, and mammals. However, it is more prominent in birds and mammals as in them the heart is completely divided into four chambers the right atrium, the right ventricle, the left atrium, and the left ventricle. The movement of blood in an organism ...
Read More →What is the difference between lymph and blood?
Question: What is the difference between lymph and blood? Solution:...
Read More →Draw diagrams showing the formation of a double bond and a triple bond between carbon atoms
Question: Draw diagrams showing the formation of a double bond and a triple bond betweencarbon atoms in C2H4and C2H2molecules. Solution: C2H4: The electronic configuration of C-atom in the excited state is: ${ }_{6} \mathrm{C}=1 s^{2} 2 s^{\prime} 2 p_{x}^{\prime} 2 p_{y}^{\prime} 2 p_{z}^{\prime}$ In the formation of an ethane molecule (C2H4), onesp2hybrid orbital of carbon overlaps asp2hybridized orbital of another carbon atom, thereby forming a C-C sigma bond. The remaining twosp2orbitals of ...
Read More →What is the difference between lymph and blood?
Question: What is the difference between lymph and blood? Solution:...
Read More →Is there any change in the hybridisation of B and N atoms as a result of the following reaction?
Question: Is there any change in the hybridisation of B and N atoms as a result of thefollowing reaction? $\mathrm{BF}_{3}+\mathrm{NH}_{3} \rightarrow \mathrm{F}_{3} \mathrm{~B} \cdot \mathrm{NH}_{3}$ Solution: Boron atom in BF3issp2hybridized. The orbital picture of boron in the excited state can be shown as: Nitrogen atom in NH3issp3hybridized. The orbital picture of nitrogen can be represented as: After the reaction has occurred, an adduct F3BNH3is formed as hybridization of B changes tosp3. ...
Read More →Why do we consider blood as a connective tissue?
Question: Why do we consider blood as a connective tissue? Solution: Connective tissues have cells scattered throughout an extra-cellular matrix. They connect different body systems. Blood is considered as a type of connective tissue because of two reasons. (i) Like the other connective tissues, blood is mesodermal in origin. (ii) It connects the body systems, transports oxygen and nutrients to all the parts of the body, and removes the waste products. Blood has an extra-cellular matrix called p...
Read More →Describe the change in hybridisation (if any) of the Al atom in the following reaction.
Question: Describe the change in hybridisation (if any) of the Al atom in the followingreaction. $\mathrm{AlCl}_{3}+\mathrm{Cl}^{-} \longrightarrow \mathrm{AlCl}_{4}^{-}$ Solution: The valence orbital picture of aluminium in the ground state can be represented as: The orbital picture of aluminium in the excited state can be represented as: Hence, it undergoessp2hybridization to give a trigonal planar arrangement (in AlCl3). To form AlCl4, the empty 3pzorbital also gets involved and the hybridiza...
Read More →What is the importance of plasma proteins?
Question: What is the importance of plasma proteins? Solution: Plasma is the colourless fluid of blood which helps in the transport of food, CO2, waste products, and salts. It constitutes about 55% of blood. About 6.8% of the plasma is constituted by proteins such as fibrinogens, globulins, and albumins. Fibrinogen is a plasma glycoprotein synthesised by the liver. It plays a role in the clotting of blood. Globulin is a major protein of the plasma. It protects the body against infecting agents. ...
Read More →Name the components of the formed elements in the blood and mention one major function of each of them.
Question: Name the components of the formed elements in the blood and mention one major function of each of them. Solution: The component elements in the blood are: (1) Erythrocytes: They are the most abundant cells and contain the red pigment called haemoglobin. They carry oxygen to all parts of the body. Red blood cells are produced continuously in some parts of the body such as the marrow of long bones, ribs, etc. There are about 4 6 million RBCs per cubic millimetre of blood. (2) Leukocytes ...
Read More →What is meant by hybridisation of atomic orbitals?
Question: What is meant by hybridisation of atomic orbitals? Describe the shapes ofsp,sp2,sp3hybrid orbitals. Solution: Hybridization is defined as an intermixing of a set of atomic orbitals of slightly different energies, thereby forming a new set of orbitals having equivalent energies and shapes. For example, one 2s-orbital hybridizes with two 2p-orbitals of carbon to form three newsp2hybrid orbitals. These hybrid orbitals have minimum repulsion between their electron pairs and thus, are more ...
Read More →Which out of NH3 and NF3 has higher dipole moment and why?
Question: Which out of NH3and NF3has higher dipole moment and why? Solution: In both molecules i.e., NH3and NF3, the central atom (N) has a lone pair electron and there are three bond pairs. Hence, both molecules have a pyramidal shape. Since fluorine is more electronegative than hydrogen, it is expected that the net dipole moment of NF3is greater than NH3. However, the net dipole moment of NH3(1.46 D) is greater than that of NF3(0.24 D). This can be explained on the basis of the directions of t...
Read More →What is Tidal volume? Find out the Tidal volume (approximate value) for a healthy human in an hour.
Question: What is Tidal volume? Find out the Tidal volume (approximate value) for a healthy human in an hour. Solution: Tidal volume is the volume of air inspired or expired during normal respiration. It is about 6000 to 8000 mL of air per minute. The hourly tidal volume for a healthy human can be calculated as: Tidal volume = 6000 to 8000 mL/minute Tidal volume in an hour = 6000 to 8000 mL (60 min) = 3.6 105mL to 4.8 105mL Therefore, the hourly tidal volume for a healthy human is approximately ...
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