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3451.	Sodium Carbonate is prepared on large scale by
Answer» SOLVAY's process BECKMANN's PLANTS Hesenclover plant adding WATER to lime ANSWER :A

3452.	Sodium carbonate is commonly used in the kitchen for making tasty crispy pakoras.
Answer» SOLUTION :False – It is sodium HYDROGENCARBONATE that is USED for MAKING pakoras.

3453.	Sodium carbonate is a basic salt because it is a salt of
Answer» strong ACID and strong BASE weak acid and weak base strong acid and weak base weak acid and strong base Solution :Sodium carbonate `(Na_(2)CO_(3))` is the salt of weak acid carbonic acid `(H_(2)CO_(3))` and a strong base sodium hydroxide (NaOH). `2NaOH+H_(2)CO_(3)rarrNa_(2)CO_(3)+2H_(2)O`

3454.	Sodium carbonate can be obtained by heating baking soda.
Answer» SOLUTION :True - We OBTAIN sodium carbonate as under : `2NaHCO_(3) OVERSET("Heat") rarr Na_(2)CO_(3)+H_(2)O+CO_(2)`

3455.	sodium bicarbonate is _____ soda, whereas sodium carbonate is _____ soda.
Answer» SOLUTION :BAKING, WASHING

3456.	Sodium bi carbonate breaks down on heating: 2NaHCO_(3)rarr Na_(2)CO_(3)+H_(2)O+CO_(2) ("Atomic mass of Na"=23, C=12, H=1, O=16) (i) How many moles of sodium bi carbonate are there in this equation? (ii) What is the mass of sodium bicarbonate used in this equation? (iii) How many moles of carbon dioxide are there in this equation?
Answer» Solution :`2NaHCO_(3)overset(Delta)rarr Na_(2)CO_(3)+H_(2)O+CO_(2)uarr` (ii) 2 moles of `NaHCO_(3)` (sodium bicarbonate) are there in the above equation. (ii) Mass of sodium bicarbonate in this equationi is mass of 2 moles of `NaHCO_(3)`. `{:("Atomic mass of 1(NA) "1xx23,=, 23g),("Atomic mass of 1(H)"=1xx1,=,1G),("Atomic mass of 1(C)"=1xx12,=,12G),("Atomic mass of 3(O)"=3xx16,=,48),(,,""ulbar("84g")):}` Mass of 1 MOLE of `NaHCO_(3)=84g` `therefore"Mass of 2 moles of "NaHCO_(3)=84xx2=168g` (iii) Number of moles of `Co_(2)` in this equation = 1 mole

3457.	Sodium bicarbonate is also known as
Answer» WASHING soda baking soda glauber's salt lime soda SOLUTION :Sodium BICARBONATE, `NaHCO_3` is also CALLED baking soda

3458.	Sodium bicarbonate can be manufactured by Solvary process where addition of brine solution to ammonium bicarbonate solution gives precipitation of sodium bicarbonate. But, its analogue, potassium bicarbonate cannot be prepared by the above process. Explain with respect to the concept of solubility product
Answer» Solution :Sodium bicarbonate has low value of solubility product. Addition of sodium chloride solution to ammonium carbonate solution results in the double DISPLACEMENT reaction that results in the precipitation of sodium bicarbonate, as ionic product. Potassium bicarbonate has HIGH value of solubility product and is highly soluble. In this case, though double displacement takes place, ionic product cannot exceed the high value of solubility product of `KHCO_(3)`. Therefore, precipitation cannot TAKE place. Hence, this method cannot be EMPLOYED for the preparation of potassium bicarbonate

3459.	Sodium atom and sodium ion
Answer» are chemically the same have the same NUMBER of protons have the same number of ELECTRONS react spontaneously with WATER ANSWER :b

3460.	Sodium and potassium are placed in the same group of modern periodic table. If the molecular formula of sodium sulphate is Na, So, then decide the molecular formula of potassium sulphate. Give reason for your answer.
Answer» Solution :Molecular formula of potassium SULPHATE : `K_(2)SO_(4)` If molecular formula of sodium sulphate is `Na_(2)SO_(4)` . It MEANS : `SO_(4)`has valency of 2 and NA has valency of 1. As, Na and K belongs to same group, they will show same valency, HENCE the formula `K_(2) SO_(4)`

3461.	Sodium and chlorine are poisonous substances but sodium chloride is edible. State reason.
Answer» Solution :Sodium chloride is a compound of sodium and chloride it is ANEW product, NEUTRAL and CHEMICALLY DIFFERENT from its CONSISTENT elemetns, hence it is edible.

3462.	What happens when a piece of sodium metal is dropped in water taken in a beaker ?
Answer» SOLUTION :HYDROGEN .

3463.	Soda water has a pH value
Answer» `GT 7` `lt 7 ` `7` `gt 14` ANSWER :B

3464.	Soda lime is a mixture of……………………
Answer» Solution :3 PARTS of `NaOH_((s))+1` PART of `CaO_((s))`

3465.	Soda ash is a salt of
Answer» STRONG ACID and strong base strong acid and WEAK base weak acid and weak base weak acid and strong base Answer :D

3466.	Soda Acid for extinguisher contains
Answer» SODIUM CARBONATE and NITRIC acid sodium hydrogen carbonate and sulphuric acid sodium carbonate andcarbonic acid sodium CHLORIDE and sulphuric acid Answer :B

3467.	Soaps can produce foam only in :
Answer» HARD water Soft water Soft and Hard water All of these Answer :B

3468.	Soaps are prepared by alkaline hydrolysis of :
Answer» INORGANIC acids Fatty acids Glycerides Alcohols Answer :B

3469.	Soaps are prepared by the alkaline hydrolysis of
Answer» sulhuric acid higher esters aldehydes fatty ACIDS ANSWER :B

3470.	Soaps and detergents are cleansing agents. Name the byproduct in the industrial production of soap.
Answer» ANSWER :GLYCERINE

3471.	Soaps and detergents are cleansing agents. How does excessive use of detergents destroy aquatic life ?
Answer» Answer :Detergents reduces the oxygen CONTENT of WATER. Detegents are not biogradable.

3472.	Soap solution appears cloudy because micelles scatter the light.
Answer» ANSWER :1

3473.	Soap has greater foaming capacity.
Answer» SOLUTION :SOAP has POOR FOAMING CAPACITY.

3474.	Soap forms a scum in hard water.
Answer» ANSWER :1

3475.	SO_2 gas is filled in soft drinks using effect of pressure.
Answer» Solution :CORRECT STATEMENT: `CO_2` GAS is filled in soft drinks using effect of PRESSURE

3476.	Smallest possible unit of a compound which has independent existence is
Answer» MOLECULE ATOM ion electron SOLUTION :molecule

3477.	Slaked lime reacts with chlorine to give
Answer» baking soda washing soda bleaching powder cment Solution :`underset("slaked LIME")(Ca(OH)_(2))+Cl_(2)to underset("bleaching powder")(CaOCl_(2))+H_(2)O`

3478.	Slag is the fusible product formed when ……………..reacts with ………….. During the extraction of metals.
Answer» SOLUTION : FLUX , GANGUE

3479.	Slag is the fusible product formed when flux reacts with gangue during the extraction of metals
Answer» SOLUTION :N/A

3480.	Size of sodium atom is bigger than that of hydrogen atom. Why?
Answer» SOLUTION :HYDROGEN ATOM contains one shell while SODIUM contains three shells.

3481.	Six elements of periodic table A, B, C, D, E and F have atomic numbers of 2, 12, 20, 18, 4 and 10 respectively (where A, B, C, D, E and F are not the chemical symbols of these elements). Based on this information, answer the following questions : Which of these elements belong to the same periods of the periodic table? Why?
Answer» Solution :First of all, write the electronic configurations of all the given six elements as follows: (2) (i) Element B (2, 8, 2) and element D (2, 8, 8) belong to the third period because they both have 3 ELECTRON shells - K, L and M each. (ii) Element E (2, 2) and element F (2, 8) belong to the second period because they both have 2 electron shells - K and L each.

3482.	Six elements of periodic table A, B, C, D, E and F have atomic numbers of 2, 12, 20, 18, 4 and 10 respectively (where A, B, C, D, E and F are not the chemical symbols of these elements). Based on this information, answer the following questions : Which of these elements are chemically (i) reactive and (ii) unreactive ?
Answer» SOLUTION :First of all, write the electronic configurations of all the given SIX elements as follows: (4) (i) (i) Elements B, C and E of group 2 are chemically reactive elements. (II) Elements A, D and F of group 18 are chemically UNREACTIVE elements.

3483.	Six elements of periodic table A, B, C, D, E and F have atomic numbers of 2, 12, 20, 18, 4 and 10 respectively (where A, B, C, D, E and F are not the chemical symbols of these elements). Based on this information, answer the following questions : Which of these elements are (i) metals and (ii) non-metals ?
Answer» Solution :FIRST of all, write the ELECTRONIC configurations of all the given SIX elements as follows: (3) (i) Elements B, C and E belonging to group 2 are metals. (ii) Elements A, D and F belonging to group 18 are non-metals (noble gases).

3484.	Six elements of periodic table A, B, C, D, E and F have atomic numbers of 2, 12, 20, 18, 4 and 10 respectively (where A, B, C, D, E and F are not the chemical symbols of these elements). Based on this information, answer the following questions : What values are indicated in a student in answering the above questions?
Answer» Solution :First of all, write the electronic configurations of all the given six elements as follows: Answering these QUESTIONS by a student are INDICATING awareness towards modern periodic classification of the elements and ability to APPLY his knowledge in SOLVING the RELATED questions.

3485.	Six elements of periodic table A, B, C, D, E and F have atomic numbers of 2, 12, 20, 18, 4 and 10 respectively (where A, B, C, D, E and F are not the chemical symbols of these elements). Based on this information, answer the following questions : Which of these elements belong to the same groups of the periodic table? Why?
Answer» Solution :First of all, write the electronic configurations of all the given six elements as follows: (1) (i) Elements B, C and E belong to the group 2 of the periodic table because all of them have an equal NUMBER of valence electrons equal to 2. (ii) Elements A, D and F also belong to the group 18 because they are all inert GASES having completely FILLED outermost electron shells with 8 valence electrons.

3486.	Single displacement reaction involves
Answer» Oxidation reduction Redox heating Answer :C

3487.	Silver was the first metal to be used in making utensils and weapons
Answer» Solution :COPPER was the first metal to be used in MAKING UTENSILS and WEAPONS.

3488.	Silver metal can displace hyfrogen gas from nitric acid
Answer» Solution :FALSE Correct statement:In the ACTIVITY series,any metals that are below hydrogen will not REACT with `HNO_(3)`

3489.	Silver is the poorest conductor of electricity.
Answer» ANSWER :F

3490.	Silver chloride on photochemical decomposition produces silver and chlorine. What is the application of this reaction ?
Answer» Solution :This REACTION finds APPLICATION in black and WHITE photography.

3491.	Silver chloride is stored in dark coloured bottle because...
Answer» it is a WHITE solid. it gives REDOX reaction. to avoid the EFFECT of SUNLIGHT. None of these Solution :to avoid the effect of sunlight.

3492.	Silver chloride decomposes into silver and chlorine by the action of ________.
Answer» SOLUTION :LIGHT. The FOLLOWING reaction takes place : `2AgCloverset("Light")(to)2Ag+Cl_(2)`

3493.	Silver anklet has got tarnished due to the formation of……..
Answer» `Ag_(2)O` `AgNO_(3)` `Ag_(2)S` AgBr Answer :A::B

3494.	Silicon is the most abundant element in the Earth's crust.
Answer» Solution :Correct statement : Oxygen is the most ABUNDANT element in the Earth.s CRUST.

3495.	Silicon is classified as ____ or ____ because it exhibits some properties of both metals and non-metals.
Answer» SOLUTION :semi-metal, METALLOID

3496.	Siliconformsa compoundwith chlorineinwhich5.6gof siliconis combinedwith 21.3g ofchlorine.Calculatethe formulaof thecompound. ( atomicmass Si = 28: Cl = 35-5).
Answer» SOLUTION : `therfore` FORMULAIS `SI Cl_(3)`.

3497.	Silicon dioxide reacts with calcium oxide to form…….
Answer» SOLUTION :CALCIUM SILICATE

3498.	Significant role of stomata in transporation is
Answer» CREATE UPWARD pressure ABSORB carbon DIOXIDE release oxygen perform TRANSPIRATION continuously Solution :absorb carbon dioxide

3499.	Siderite is a _______ ore .
Answer» SOLUTION :CARBONATE

3500.	S.I. unit of temperature is
Answer» KELVIN `""^@C` `""^@F` both `""^@C` and K Answer :A

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