ECAT Chemistry Online Test With Answers

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ECAT Chemistry Online Test

Sr. # Questions Answers Choice
1 Kspvalue for PbSO4= 1.8 x 10-8mole2dm-6. The maximum concentration of Pb++ions is 1.34 x 10<sup>-4</sup>mole dm<sup>-3</sup> 1.8 x 10<sup>-4</sup> 3.6 x 10<sup>-16</sup>mole dm<sup>-3</sup> 1.0 x 10<sup>-8</sup>mole dm<sup>-3</sup>
2 The solubility product of AgCl is 2.0 x 10-10mole 2dm-6. The maximum concentration of Ag+ions in the solution is 2.0 x 10<sup>-10</sup>mole dm<sup>-3</sup> 1.41 x 10<sup>-5</sup>mole dm<sup>-3</sup> 1.0 x 10<sup>-10</sup> 4.0 x 10<sup>-20</sup>mole dm<sup>-3</sup>
3 Product of concentration of ions raised to the power equal to the co-efficient of ions in balanced equation for saturated solution of a salt is called Ionic product Equilibrium constant K<sub>c</sub> K<sub>w</sub> Solubility product (K<sub>sp</sub>)
4 Buffers having pH less than 7 are made Mixture of weak acid + salt of it with strong base Mixture of weak acid + salt of it with weak base Mixture of weak base + salt of it with strong acid Mixture of weak base + salt of it with weak base
5 The relation between Kc and Kp is
6 pH of the human blood which is essentially maintained constant due to carbonates, biocarbonates, phosphates etc., is 7.00 7.25 7.35 7.47
7 A buffer solution of 0.1 molar HCOOH and 0.1 molar HCCONa has pH = 3.78 To is 0.01 molar HCl is added, then pH of the buffer solution becomes 2.78 4.78 3.78 3.70
8 If pH of buffer of 1 mole dm-3of HCOOH + 0.1 mole dm-3HCOONa having pKa = 3.78 is 1.78 2.78 3.78 4.78
9 pH of 0.1 molar HCl solution is 1 zero 13 14
10 A buffer of a 0.09 molar acetic acid and 0.11 molar sodium acetate has pH = 4.83. If 0.01 mole NaOH in 1 dm3of the buffer solution is added, then pH of the buffer becomes 4.74 4.92 5.0 4.0
11 pH of water is 7, if 0.01 M NaOH is added, than its pH is 12 14 zero 10
12 pH of 1 molar NaOH is 7 zero 14 10
13 pKb value of NH4OH is 4.74. If the concentration of NH4OH is 1 molar containing 0.1 molar NH4Cl, then pH of this buffer will be 3.74 10.26 4.74 9.26
14 ph of the buffer CH3COOh + CH3COONa is 3.76. If the mixture contains 1 molar acetic acid and 0.1 molar sodium acetate, then pKa of this buffer is 3.76 4.76 5.76 6.76
15 The best buffer is prepared when molar concentrations of the salt and acid are equal, then its pH and pKa value are related pH = pKa pH &lt; pKa pH &gt; pKa pH x pKa = 14
16 pH and pKa of the buffer are related by Henderson equation which is
17 Kbvalue of NH4OH is 1.81 x 10-5and its conjugate acid has Ka= 5.7 x 10-10pKb of the base is 4.74, pKa of its conjugate acid is -4.74 4.74 10 9.26
18 strength of an acid can be determined by P<sup>ka</sup> P<sup>kp</sup> P<sup>oH</sup> P<sup>kw</sup>
19 When fused PbBr2is electrolyed then Bromine appears at cathode Lead deposited at the cathode Lead appears at the anode None of these happens
20 An electrochemical cell is based upon Acid-base reaction Redox reaction Nuclear reaction None of the above
21 Sodium metal is obtained by the electrolysis of fused NaCl in cell is called Nelson's cell Down's cell Daniell cell Voltaic cell
22 -1.10 V +1.10 V -0.42 V +0.42 V
23 Iodine can oxidise iron Bromine can oxidise iron Iodine can oxidise bromine Iron can oxidise bromine
24 A strong reducing agent A strong oxidising agent Better oxidising agent than hydrogen Less reducing agent than hydrogen
25 A standard hydrogen electrode (S.H.E) consists of a platinized platinum electrode dipped in 1 molar solution of H+ions and hydrogen gas is passed at a pressure of One pascal One kilo pascal One atmoshpere Then atmoshpere
26 Adding H<sub>2</sub>O and H<sup>+</sup>ions Adding OH<sup>-</sup>ions Adding O<sup>2</sup>molecules Adding O atoms
27 Corrosion reaction are Spontaneous redox reaction Non-spontaneous acid-base reactions Spontaneous acid-base reactions None of these
28 Standard reduction of Zn = -0.76 V and that of Ni is -0.25 V. On coupling them by a salt bridge which of these will act as anode Salt bridge will act as anode Zn will act as anode Ni will act as anode None of these
29 Zn does not displace Mg from MgSO4solution because Zn is more electropositive than Mg Zn is below Mg in electropositive series Zn is above Mg in electrochemical series Zn is trivalent Mg is divalent
30 Fe can displace Cu form CuSO4solution because Fe is ferromagnetic Fe is below Cu in electrochemical series Fe is above Cu in electrochemical series Fe exists in divalent oxidation state
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