Gases possess characteristic critical temperature
Question: Gases possess characteristic critical temperature which depends upon the magnitude of intermolecular forces between the particles. Following are the critical temperatures of some gases. Gases H2 He O2 N2 Critical temperature in Kelvin 33.2 5.3 154.3 126 From the above data what would be the order of liquefaction of these gases? Start writing the order from the gas liquefying first (i) H2, He, O2, N2 (ii) He, O2, H2, N2 (iii) N2, O2, He, H2 (iv) O2, N2, H2, He Solution: Option (iv) is t...
Read More →As the temperature increases,
Question: As the temperature increases, the average kinetic energy of molecules increases. What would be the effect of the increase of temperature on pressure provided the volume is constant? (i) increases (ii) decreases (iii) remains the same (iv) becomes half Solution: Option (i) is the answer....
Read More →The pressure of a 1:4 mixture of dihydrogen
Question: The pressure of a 1:4 mixture of dihydrogen and dioxygen enclosed in a vessel is one atmosphere. What would be the partial pressure of dioxygen? (i) 0.8105 atm (ii) 0.008 Nm2 (iii) 8104Nm2 (iv) 0.25 atm Solution: Option (iii) is the answer....
Read More →Dipole-dipole forces act between
Question: Dipole-dipole forces act between the molecules possessing permanent dipole. Ends of dipoles possess partial charges. The partial charge is (a) more than unit electronic charge. (b) equal to unit electronic charge. (c) less than unit electronic charge. (d) double the unit electronic charge. Solution: (c) Partial charge is a small charge developed by displacement of electrons. It is less than unit electronic charge and is represented as+or...
Read More →The interaction energy of London force
Question: The interaction energy of London force is inversely proportional to sixth power of the distance between two interacting particles but their magnitude depends upon (a) charge of interacting particles. (b) mass of interacting particles. (c) polarisability of interacting particles. (d) strength of permanent dipoles in the particles. Solution: (c) London dispersion forces operate only over very short distance. The energy of interaction varies as 1/(distance between two interacting particle...
Read More →A plot of volume (V) versus temperature (T)
Question: A plot of volume (V) versus temperature (T)fora gas at constant pressure is a straight line passing through the origin. The plots at different values of pressure are shown in the figure. Which , of the following order of pressure is correct for this gas? (a)P1P2 P3P4 (b) P1=p2=p3=p4 (c) P1P2P3P4 (d) pxp2=p3p4 Solution: (c) At a particular temperature pV= constant. Thus, P1V1=P2V2=P3V3=P4V4 As V1 V2 V3 V4, therefore, P1P2 P3 P4....
Read More →Which of the following properties
Question: Which of the following properties of water can be used to explain the spherical shape of rain droplets? (a)Viscosity (b)Surface tension (c)Critical phenomena (d)Pressure Solution: (b) Due to surface tension, the surface of the water drops is under tension and tends to take spherical shape to reduce the tension....
Read More →Find a point on the x-axis which is equidistant from the points A
Question: Find a point on the x-axis which is equidistant from the points A (7, 6) and B(- 3, 4). Solution: Let the point on x-axis be P(x, 0). Given: Point $P(x, 0)$ is equidistant from points $A(7,6)$ and $B(-3,4)$ i.e., distance of $P$ from $A=$ distance of $P$ from $B$ $\Rightarrow \sqrt{(x-7)^{2}+36}=\sqrt{(x+3)^{2}+16}$ Squaring both sides, $\Rightarrow(x-7)^{2}+36=(x+3)^{2}+16$ $\Rightarrow x^{2}-14 x+49+36=x^{2}+6 x+9+16$ $\Rightarrow-20 x=-60$ $\Rightarrow x=3$ Therefore, the point on t...
Read More →Find the angle to intersection of the following curves :
Question: Find the angle to intersection of the following curves : $x^{2}+y^{2}-4 x-1=0$ and $x^{2}+y^{2}-2 y-9=0$ Solution: Given: Curves $x^{2}+y^{2}-4 x-1=0 \ldots(1)$ $\ x^{2}+y^{2}-2 y-9=0$ First curve is $x^{2}+y^{2}-4 x-1=0$ $\Rightarrow x^{2}-4 x+4+y^{2}-4-1=0$ $\Rightarrow(x-2)^{2}+y^{2}-5=0$ Now, Subtracting $(2)$ from $(1)$, we get $\Rightarrow x^{2}+y^{2}-4 x-1-\left(x^{2}+y^{2}-2 y-9\right)=0$ $\Rightarrow x^{2}+y^{2}-4 x-1-x^{2}-y^{2}+2 y+9=0$ $\Rightarrow-4 x-1+2 y+9=0$ $\Rightarr...
Read More →A person living in Shimla observed
Question: A person living in Shimla observed that cooking food without using pressure cooker takes more time. The reason for this observation is that at high altitude (a) pressure increases. (b) temperature decreases. (c) pressure decreases. (d) temperature increases. Solution: (c) At high altitudes, pressure is low. Hence, boiling takes place at lower temperature and therefore, cooking takes more time. In pressure cooker, pressure is high and hence boiling point increases....
Read More →Find the angle to intersection of the following curves :
Question: Find the angle to intersection of the following curves : $2 y^{2}=x^{3}$ and $y^{2}=32 x$ Solution: Given: Curves $2 y^{2}=x^{3} \ldots(1)$ $\ y^{2}=32 x$ .....(2) First curve is $2 y^{2}=x^{3}$ Differentiating above w.r.t $x$, $\Rightarrow 4 y \cdot \frac{d y}{d x}=3 x^{2}$ $\Rightarrow m_{1}=\frac{d y}{d x}=\frac{3 x^{2}}{4 y} \ldots(3)$ Second curve is $y^{2}=32 x$ $\Rightarrow 2 y \cdot \frac{d y}{d x}=32$ $\Rightarrow y \cdot \frac{d y}{d x}=16$ $\Rightarrow m_{2}=\frac{d y}{d x}=...
Read More →What is meant by the term average
Question: What is meant by the term average bond enthalpy? Why is there a difference in bond enthalpy of OH bond in ethanol (C2H5OH) and water? Solution: Similar bonds in a molecule do not have the same bond enthalpies. Mainly the term average bond enthalpy is used in polyatomic molecules. It is obtained by dividing bond dissociation enthalpy by the number of bonds broken. The bond enthalpy of OH bond is different in ethanol and water because of the difference in electronegativity of hydrogen an...
Read More →All the C—O bonds in carbonate ion
Question: All the CO bonds in carbonate ion (CO2-3) are equal in length. Explain Solution: Carbonate ion is present in the form of a resonating structure. These structures are equivalenting to nature. Resonance all 3 C-O bonds get a double character in one of the resonating structures....
Read More →If a point P(x, y) is equidistant from the points A
Question: If a point P(x, y) is equidistant from the points A(6, -1) and B(2, 3), find the relation between x and y. Solution: Given: Point P(x, y) is equidistant from points A(6, -1) and B(2, 3) i.e., distance of P from A = distance of P from B $\Rightarrow \sqrt{(x-6)^{2}+(y+1)^{2}}=\sqrt{(x-2)^{2}+(y-3)^{2}}$ Squaring both sides $\Rightarrow(x-6)^{2}+(y-1)^{2}=(x-2)^{2}+(y-3)^{2}$ $\Rightarrow x^{2}-12 x+36+y^{2}-2 y+1=x^{2}-4 x+4+y^{2}-6 y+9$ $\Rightarrow-12 x+36+2 y+1=-4 x+4-6 y+9$ $\Righta...
Read More →Predict the shapes of the following
Question: Predict the shapes of the following molecules based on hybridisation. BCl3, CH4, CO2, NH3 Solution: In compound BCl3, Boron has sp2-hybridisation and the shape is Triangular Planar. In methane CH4, Carbon has sp3 -hybridization and shape are Tetrahedral. In carbon dioxide CO2, carbon has sp-hybridisation and shape is Linear. In ammonia NH3, nitrogen has sp3-hybridisation and shape is Pyramidal....
Read More →Elements X, Y and Z have 4,
Question: Elements X, Y and Z have 4, 5 and 7 valence electrons respectively. (i) Write the molecular formula of the compounds formed by these elements individually with hydrogen. (ii) Which of these compounds will have the highest dipole moment? Solution: (i); XH4, H3Y, and HZ Hydrogen has only one electron in its outermost shell it shares one electron to form a covalent bond or accepts or donates one electron to form an ionic bond. (ii) The compound HZ has a linear shape and the difference in ...
Read More →Group the following as linear
Question: Group the following as linear and non-linear molecules : H2O, HOCl, BeCl2, Cl2O Solution: BeCl2has a linear structure HOCl is also non-linear in structure. H2O has a V-shaped structure. Cl2O has a V-shaped structure....
Read More →Find the distance of the point P(6, -6) from the origin.
Question: Find the distance of the point P(6, -6) from the origin. Solution: Distance of point $P(6,-6)$ from origin $(0,0)=$ $\sqrt{(0+6)^{2}+(0-6)^{2}}$ $=\sqrt{36+36}$ $=6 \sqrt{2}$ units Therefore, the distance of the point $P$ from the origin is $6 \sqrt{2}$ units....
Read More →Explain why CO32- ion cannot
Question: Explain why CO32-ion cannot be represented by a single Lewis structure. How can it be best represented? Solution: Solution: Carbonate ion is present in the form of a resonating hybrid structure. These structures are equivalent. Resonance all 3 C-O bonds get a double character in one of the resonating structures. Thus, all the bonds are equivalent and have equal length hence carbonate ion cannot be represented by a single Lewis structure....
Read More →Arrange the following bonds
Question: Arrange the following bonds in order of increasing ionic character giving a reason NH, FH, CH and OH Solution: The ionic character is greater in the molecules that are having the greatest electronegativity difference because the electron pair shifts toward a more electronegative atom increasing the ionic character. Thus, the ionic character order will be: C-HN-HO-H F-H...
Read More →Find the distance between the points:
Question: Find the distance between the points: (i) $A(2,-3)$ and $B(-6,3)$ (ii) $C(-1,-1)$ and $D(8,11)$ (iii) $P(-8,-3)$ and $Q(-2,-5)$ (iv) $R(a+b, a-b)$ and $S(a-b, a+b)$ Solution: (i) Formula Used: Distance between any two points $\mathrm{A}\left(\mathrm{x}_{1}, \mathrm{y}_{1}\right)$ and $\mathrm{B}\left(\mathrm{x}_{2}, \mathrm{y}_{2}\right)=$ $\sqrt{\left(x_{2}-x_{1}\right)^{2}+\left(y_{2}-y_{1}\right)^{2}}$ Distance between $A(2,-3)$ and $B(-6,3)$ $=\sqrt{(-6-2)^{2}+(3-(-3))^{2}}$ $=\sqr...
Read More →What is an ionic bond?
Question: What is an ionic bond? With two suitable examples explain the difference between an ionic and a covalent bond? Solution: when a positively charged ion forms a bond with a negatively charged ions and one atom transfers electrons to another. An example of an ionic bond is the chemical compound Sodium Chloride (NaCl). The difference between an ionic bond and covalent bond is that An ionic bond essentially donates an electron to the other atom participating in the bond, while electrons in ...
Read More →Give reasons for the following :
Question: Give reasons for the following : (i) Covalent bonds are directional bonds while ionic bonds are nondirectional. (ii) The water molecule has a bent structure whereas carbon dioxide molecule is linear. (iii) Ethyne molecule is linear. Solution: (i) A covalent bond is formed by the overlapping of atomic orbitals. The direction of overlapping gives the direction of the bond. (ii) In a water molecule, the oxygen atom is sp3 hybridized and has two lone pairs of electrons. (iii) In the ethyne...
Read More →What is the effect of the following processes
Question: What is the effect of the following processes on the bond order in N2 and O2? (i) N2 N2+ + e- (ii) O2 O2+ + e- Solution: (i) N2 is having 14 electrons when it donates one electron, these electrons are removed from the Bonding molecular orbital. BO for N2 = 3 (ii) O2 has 16 electrons, 8 electrons in the molecular orbitals and 4 in the antibonding molecular orbitals. BO for O2 = 2...
Read More →The energy of σ2pz molecular orbital is greater
Question: The energy of 2pz molecular orbital is greater than 2px and 2py molecular orbitals in nitrogen molecule. Write the complete sequence of energy levels in the increasing order of energy in the molecule. Compare the relative stability and the magnetic behaviour of the following species : N2, N2+, N2-, N22+ Solution: The general sequence of the energy level of the molecular orbital is 1s *1s 2s *2s 2px = 2py 2pz N2 1s2 *1s2 2s2 *2s2 2p2x = 2p2y 2p2z N2+ 1s2 *1s2 2s2 *2s2 2p2x = 2p2y 2p1z N...
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