You have four test tubes, A, B, C and D containing sodium carbonate, sodium chloride, lime water and blue litmus solutions respectively. Out of these the material of which test tube/ test tubes would be suitable for the correct test of acetic/ethanoic acid?
only A
A and B
B and C
B and C
D.
B and C
The chemical reaction between ethanoic (acetic) acid and sodium carbonate is:
2CH3COOH + Na2CO3 → 2 CH3COONa + CO2 + H2O
On passing CO2 gas through lime water, the lime water turns milky. The milky appearance of lime water is due to the formation of solid calcium carbonate (CaCO3).
Reaction:
Ca(OH)2 + CO2 → CaCO3 + H2O
therefore, out of four test tubes A, B, C and D, only A and D test tubes would be suitable for the correct test of acetic/ethanoic acid.
Acetic acid also reacts with lime water to give calcium acetate (CH3COO)2Ca) as a product. But here it is not considered as a correct test of acetic/ethanoic acid.
Reaction:
2 CH3COOH + Ca(OH)2 → (CH3COO)2Ca + 2H2O
Hence, the correct answer is the option (d).
A student while observing an embryo of a gram seed listed various parts of the embryo as listed below :
Testa, Micropyle, Cotyledon, Tegmen, Plumule, Radicle. On examining the list the teacher commented that only three parts are correct. Select these three correct parts :
Cotyledon, Testa, Plumule
Cotyledon, Plumule, Radicle
Cotyledon, Tegmen, Radicle
Cotyledon, Tegmen, Radicle
Three students A, B and C focussed a distant building on a screen with the help of a concave mirror. To determine focal length of the concave mirror they measured the distances as given below:
Student A : From mirror to the screen
Student B : From building to the screen
Student C : From building to the mirror
Who measured the focal length correctly
Mustard oil and calcium hydroxide
Castor oil and calcium hydroxide
Turpentine oil and sodium hydroxide
Turpentine oil and sodium hydroxide
A student took four test tubes P, Q, R and S and filled about 8 mL of distilled water in each. After that he dissolved an equal amount of Na2SO4 in P, K2SO4 in Q, CaSO4 in R and MgSO4 in S. On adding an equal amount of soap solution and shaking each test tube well, a good amount of lather will be obtained in the test tubes,
P and Q
P and R
P, Q and S
P, Q and S
Write the molecular formula of first two members of homologous series having functional group –Cl.
If you focus the image of a distant object, whose shape is given
below, on a screen using a convex lens,
the shape of the image of this object on the screen would be:
Select the set of homologous organs from the following:
Wings of pigeon and a butterfly
Wings of bat and a pigeon
Forelimbs of cow, a duck and a lizard
Forelimbs of cow, a duck and a lizard
In the following diagram the correctly marked angles are:
∠ A and ∠ e
∠ i, ∠ A and ∠ D
∠ A, ∠ r and ∠ e
∠ A, ∠ r and ∠ e
The correct sequencing of the angle of incidence, the angle of emergence, the angle of refraction and lateral displacement shown in the following diagram by digits 1, 2, 3 and 4 is:
2, 4, 1, 3
2, 1, 4, 3
1, 2, 4, 3
1, 2, 4, 3