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Lungs do not collapse between breaths an...

Lungs do not collapse between breaths and some air always remains in the lungs which can never be expelled because
1. there is a negative pressure in the lungs
2. there is a negative intrapleural pressure pulling at the lung walls
3. there is a positive intrapleural pressure
4. pressure in the lungs is higher than the atmospheric pressure

A

there is a negative pressure in the lungs

B

there is a negative intrapleural presure pulling at the lung walls

C

there is a positive intrapleural pressure

D

pressure in the lungs is higher than the atmospheric pressure

Text Solution

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The correct Answer is:
B
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(b) What is the air pressure within the lungs of man?

Consider the following statements 1. Xylem vessels are semi-permeable 2. Sieve tubes translocate only solutes 3. Xylem vessels do not have a turgor pressure 4. Companion cells help in maintaining pressure gradient in the sieve tubes . Which of the statements given above are correct ?

Knowledge Check

  • Addition of non-volatile solute to a solvent always increases the colligative properties such as osmotic pressure. Delta P . Delta T_b and Delta T_f . All these colligative properties are directly proportional to molality if solutions are dilute. The increases in colligative properties on addition of non-volatile solute is due to increases in number of solute particles. 1 g mixture of glucose and urea present in 250mL aqueous solution shows the osmotic pressure of 0.74 atm at 27^@C . Assuming solution to be dilute which are correct ? 1. Percentage of urea in mixture is 17.6. 2. Relative lowering in vapour pressure of this solution is 5.41 xx 10^(-4) . 3. The solution will boil at 100.015^@C . if k_b of water is 0.5 k molality^(-1) . 4. If glucose is replaced by same amount of sucrose the solution will show higher osmotic pressure at 27^@C . 5. If glucose is replaced by same amount of NaCI, the solution will show lower osmotic pressure at 27^@C .

    A
    1,2,3
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  • If the composition of the system does not change with time, the system is said to be in chemical equilibrium. itis the state in which net reaction of a system Is zero. in another words we can say that in reversible reactions, a stage is reached when the rate of transformation of reactants into products equals the rate of transformation of products into reactants. At this stage, the composition of reactants and products does not change with time. This does not mean that the reaction has ceased, as both reverse and forward reactions are still taking place but with equal speed. Such equilibria are called dynamic equilibria, Let us consider a reaction of the type A_(g) + B_(g) iff C_(g) + D_(g) K_c = ([C][D])/([A][B]) where K_c is equilibrium constant when the ratio of the concentrations of the product to reactants K_p = (P_C xx P_O)/(P_A xx P_B) where K_P is the equilibrium constant for the ratio of partial pressure of products to reactants. The relation between K_P and K_C is as follows K_P = K_C(RT)^(Deltan) For the reaction NH_2COONH_4(s) iff 2NH_3(g) + CO_2(g) The equilibrium constant K_p = 2.9 xx 10^-5 atm^3 . The total pressure of gases at equilibrium when 1 mole of reactant was heated will be

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    0.0194 atm
    B
    0.0388 atm
    C
    0.0580 atm
    D
    0.0667 atm

  • If the composition of the system does not change with time, the system is said to be in chemical equilibrium. itis the state in which net reaction of a system Is zero. in another words we can say that in reversible reactions, a stage is reached when the rate of transformation of reactants into products equals the rate of transformation of products into reactants. At this stage, the composition of reactants and products does not change with time. This does not mean that the reaction has ceased, as both reverse and forward reactions are still taking place but with equal speed. Such equilibria are called dynamic equilibria, Let us consider a reaction of the type A_(g) + B_(g) iff C_(g) + D_(g) K_c = ([C][D])/([A][B]) where K_c is equilibrium constant when the ratio of the concentrations of the product to reactants K_p = (P_C xx P_O)/(P_A xx P_B) where K_P is the equilibrium constant for the ratio of partial pressure of products to reactants. The relation between K_P and K_C is as follows K_P = K_C(RT)^(Deltan) The mass ratio of steam and hydrogen is found to be 1:2 at equilibrium. 3 Fe(s) + 4H_2O(g) iff Fe_3O_4(s) + 4H_2(g) The value of equilibrium constant (K_C) for the above reaction is

    A
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    B
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    C
    `0.75 xx 10^2`
    D
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