Why is Fe(OH)3 colloid positively charged,
Question: Why is Fe(OH)3 colloid positively charged, when prepared by adding FeCl3 to hot water? Solution: When FeCl3 is added to hot water, the hydrated ferric oxide is formed. This hydrated ferric oxide preferably adsorbs Fe3+ ions resulting in the positively-charged colloid....
Read More →Why does the bleeding stop by
Question: Why does the bleeding stop by rubbing moist alum? Solution: Moist alum has highly charged Al3+ and SO42- ions which neutralize the charged protein molecules present in the blood. This results in the coagulation of blood proteins and stops bleeding....
Read More →Mark the tick against the correct answer in the following:
Question: Mark the tick against the correct answer in the following: Define $*$ on $\mathrm{Q}-\{-1\}$ by $\mathrm{a} * \mathrm{~b}=\mathrm{a}+\mathrm{b}+\mathrm{ab}$. Then, $*$ on $\mathrm{Q}-\{-1\}$ is A. commutative but not associative B. associative but not commutative C. neither commutative nor associative D. both commutative and associative Solution: According to the question, $R=\{(a, b): a * b=a+b+a b\}$ Formula $*$ is commutative if $a * b=b * a$ $*$ is associative if $(a * b) * c=a *(b...
Read More →Based on Hardy-Schulze rule explain
Question: Based on Hardy-Schulze rule explain why the coagulating power of phosphate is higher than chloride. Solution: According to Hardy-Schulze rule, the coagulation property of an electrolyte depends upon the valency of the coagulation ion. Higher the charge on flocculating ion smaller is the amount of electrolyte required for precipitation. Phosphate ion has -3 charge while chloride ion carries only -1 charge. So coagulating power of phosphate is higher than chloride....
Read More →Evaluate the following integrals:
Question: Evaluate the following integrals: $\int \cos \sqrt{x} d x$ Solution: Let $I=\int \cos \sqrt{x} d x$ $\sqrt{\mathrm{X}}=\mathrm{t} ; \mathrm{x}=\mathrm{t}^{2}$ $d x=2 t d t$ $=\int 2 t \cos t d t$ $I=2 \int t \cos t d t$ Using integration by parts, $=2\left(\mathrm{t} \times \sin \mathrm{t}-\int \sin \mathrm{t} \mathrm{dt}\right)$ $=2(\mathrm{t} \sin \mathrm{t}+\cos \mathrm{t})+\mathrm{c}$ Replace the value of $t, I=2(\sqrt{x} \sin \sqrt{x}+\cos \sqrt{x})+c$...
Read More →How will you distinguish between
Question: How will you distinguish between the dispersed phase and dispersion medium in an emulsion? Solution: An emulsion is a dispersion of one liquid in another immiscible liquid. The dispersed phase is always present in fewer amounts than the dispersion medium....
Read More →How does the precipitation of colloidal
Question: How does the precipitation of colloidal smoke take place in Cottrell precipitator? Solution: Cottrell precipitator is a filtration device that removes the fine particles like dust and smoke from a flowing gas. It neutralizes the charge on carbon particles....
Read More →Why does leather get hardened
Question: Why does leather get hardened after tanning? Solution: When leather is soaked in tannin, coagulation takes place due to the interaction of positively charged animal skin and negatively charged tannin. Thus leather gets hardened....
Read More →Why are some medicines more effective
Question: Why are some medicines more effective in the colloidal form? Solution: The colloidal solution has a larger surface area than a true solution. The surface area is directly proportional to the rate of assimilation in our body. So most of the medicines act more effective in colloidal form....
Read More →Evaluate the following integrals:
Question: Evaluate the following integrals: $\int \log _{10} x d x$ Solution: Let $I=\int \log _{10} x d x$ $=\int \frac{\log x}{\log 10} d x$ $=\frac{1}{\log 10} \int 1 \times \log x d x$ Using integration by parts, $=\frac{1}{\log 10}\left(\log x \int d x-\int \frac{d}{d x} \log x \int 1 d x\right)$ We know that $\frac{\mathrm{d}}{\mathrm{dx}} \log \mathrm{x}=\frac{1}{\mathrm{x}}$ $=\frac{1}{\log 10}\left(x \log x-\int \frac{1}{x} x x d x\right)$ $=\frac{1}{\log 10}\left(x \log x-\int d x\righ...
Read More →Mark the tick against the correct answer in the following:
Question: Mark the tick against the correct answer in the following: Let $Z^{+}$be the set of all positive integers. Then, the operation $*$ on $Z^{+}$defined bya $* b=a^{b}$ is A. commutative but not associative B. associative but not commutative C. neither commutative nor associative D. both commutative and associative Solution: According to the question, $\mathrm{Q}=\{$ All integers $\}$ $\mathrm{R}=\left\{(\mathrm{a}, \mathrm{b}): \mathrm{a}^{*} \mathrm{~b}=\mathrm{a}^{\mathrm{b}}\right\}$ F...
Read More →Evaluate the following integrals:
Question: Evaluate the following integrals: $\int \frac{x+\sin x}{1+\cos x} d x$ Solution: Let $I=\int \frac{x+\sin x}{1+\cos x} d x$ $1+\cos x$ can be written as, $2 \cos ^{2} \frac{x}{2}$ and $\sin x$ can be written as $2 \sin \frac{x}{2} \cos \frac{x}{2}$ $=\int \frac{x}{2 \cos ^{2} \frac{x}{2}} d x+\int \frac{2 \sin \frac{x}{2} \cos \frac{x}{2}}{2 \cos ^{2} \frac{x}{2}} d x$ $=\frac{1}{2} \int x \sec ^{2} \frac{x}{2}+\int \tan \frac{x}{2} d x$ Using integration by parts, $=\frac{1}{2}\left[x...
Read More →Mark the tick against the correct answer in the following:
Question: Mark the tick against the correct answer in the following: Let $Z$ be the set of all integers. Then, the operation * on $Z$ defined by $a * b=a+b-a b$ is A. commutative but not associative B. associative but not commutative C. neither commutative nor associative D. both commutative and associative Solution: According to the question, $\mathrm{Q}=\{$ All integers $\}$ $R=\{(a, b): a * b=a+b-a b\}$ Formula * is commutative if $\mathrm{a}^{*} \mathrm{~b}=\mathrm{b}^{*} \mathrm{a}$ $*$ is ...
Read More →Evaluate the following integrals:
Question: Evaluate the following integrals: $\int \frac{\log (x+2)}{(x+2)^{2}} d x$ Solution: Let I $=\int \frac{\log (x+2)}{(x+2)^{2}} \mathrm{dx}$ $\frac{1}{x+2}=t$ $\frac{-1}{(x+2)^{2}} d x=d t$ $I=-\int \log \left(\frac{1}{t}\right) d t$ Using integration by parts, $=-\int \log \mathrm{t}^{-1} \mathrm{dt}$ $=-\int 1 \times \log \mathrm{t}^{-1} \mathrm{dt}$ We know that, $\frac{d}{d t} \log t=\frac{1}{t}$ and $\int d t=t$ $\mathrm{I}=\log \mathrm{t} \int \mathrm{dt}-\int\left(\frac{\mathrm{d}...
Read More →How do emulsifying agents stabilise
Question: How do emulsifying agents stabilise the emulsion? Solution: Emulsifying agents stabilize the emulsion by forming an interfacial film between suspended particle and dispersion medium. For example, agar is an emulsifying agent used in food....
Read More →A colloid is formed by adding FeCl3
Question: A colloid is formed by adding FeCl3 in excess of hot water. What will happen if excess sodium chloride is added to this colloid? Solution: FeCl3 when added into hot water, it forms hydrated ferric oxide, which is a positively charged sol due to absorption of Fe3+ ions. On adding NaCl the negatively charged chloride ions neutralize the positive charge of the solution and coagulation of the sol takes place....
Read More →Mark the tick against the correct answer in the following:
Question: Mark the tick against the correct answer in the following: let $Z$ be the set of all integers and let $a * b=a-b+a b$. Then, $*$ is A. commutative but not associative B. associative but not commutative C. neither commutative nor associative D. both commutative and associative Solution: According to the question , $\mathrm{Q}=\{$ All integers $\}$ $R=\{(a, b): a * b=a-b+a b\}$ Formula $*$ is commutative if $a * b=b * a$ $*$ is associative if $(a * b) * c=a *(b * c)$ Check for commutativ...
Read More →Evaluate the following integrals:
Question: Evaluate the following integrals: $\int \frac{\log (\mathrm{x}+2)}{(\mathrm{x}+2)^{2}} \mathrm{~d} \mathrm{x}$ Solution: Let I $=\int \frac{\log (x+2)}{(x+2)^{2}} \mathrm{dx}$ $\frac{1}{x+2}=t$ $\frac{-1}{(x+2)^{2}} d x=d t$ $I=-\int \log \left(\frac{1}{t}\right) d t$ Using integration by parts, $=-\int \log \mathrm{t}^{-1} \mathrm{dt}$ $=-\int 1 \times \log \mathrm{t}^{-1} \mathrm{dt}$ We know that, $\frac{\mathrm{d}}{\mathrm{dt}} \log \mathrm{t}=\frac{1}{\mathrm{t}}$ and $\int \mathr...
Read More →What causes Brownian motion
Question: What causes Brownian motion in colloidal dispersion? Solution: Brownian motion is due to the collision between the colloidal particles and with the dispersion medium. The movement results in the stabilisation of the colloidal solution....
Read More →What happens when the electric field
Question: What happens when the electric field is applied to a colloidal solution? Solution: When an electric field is applied to a colloidal solution, colloidal particles move towards different electrode depending on their respective charge....
Read More →Why do we add alum to purify water?
Question: Why do we add alum to purify water? Solution: Alum is KAl(SO4)2which is called potassium aluminium sulphate. when added react with alkaline bicarbonates and forms a gelatinous precipitate. When it is added to water they attract the colloidal particles and settles down at the bottom of the container....
Read More →What is collodion?
Question: What is collodion? Solution: Collodion is a 4% solution of nitrocellulose prepared in a mixture of alcohol and ether. it is the flammable and syrupy solution....
Read More →Gelatin which is a peptide is added
Question: Gelatin which is a peptide is added in icecreams. What can be its role? Solution: Gelatin acts as an emulsifying agent which is a hydrophilic colloid. They absorb the water content in the ice-cream and also a good source of protein. They also give a soft texture and shiny appearance to ice-cream....
Read More →How does it become possible to cause
Question: How does it become possible to cause artificial rain by spraying silver iodide on the clouds? Solution: Clouds carry a charge as they are colloids. Silver iodide AgI being an electrolyte helps in coagulation process between colloidal particles of water in the cloud. Thus it forms bigger raindrops causing artificial rain. AgI is usually sprayed from an aeroplane or remote-controlled rockets....
Read More →What happens when gelatin
Question: What happens when gelatin is mixed with gold sol? Solution: When gelatin is mixed with gold sol, gelatin forms a protective layer on gold sol, thus preventing coagulation. So gold sol becomes stabilized by adding gelatin, which is a lyophilic sol....
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