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Posted by Khushi 💕 48 minutes ago
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Posted by Vansh Jamwal an hour ago
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Gaurav Seth an hour ago
Hydrogen gas and zinc sulphate are formed when zinc granules are treated with sulphuric acid.
<i>Zn + H2SO4 ⇨ ZnSO4 + H2</i>
Zinc chloride and hydrogen gas are formed, when zinc granules are treated with hydrochloric acid.
<i>Zn + 2HCl ⇨ ZnCl2 + H2</i>
Similarly, hydrogen gas and zinc nitrate are formed when zinc granules are treated with nitric acid.
<i>Zn + 2HNO3 ⇨ Zn(NO3 )2 + H2</i>
Since, zinc is less reactive than sodium, thus no reaction takes place when zinc granules are treated with sodium chloride.
Sodium zincate and hydrogen gas are formed when zinc granules are treated with sodium hydroxide and water.
<i>Zn + 2H2O + 2NaOH ⇨ Na2Zn(OH)4 + H2</i>
Posted by Khushi 💕 an hour ago
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Posted by Prince Nishad 2 hours ago
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Gaurav Seth an hour ago
A mixture or an alloy of mercury with a number of metals or alloys such as sodium as well as with some non-metals is known as amalgam.
Uses:
1. Sodium is highly reactive metal and therefore it is difficult to transport. To lower its reactivity, it is mixed with mercury.
2. Dental amalgam is a mixture of mercury and a silver-tin alloy and is used for fillings in teeth.
Amalgam fillings are often known as “silver fillings.” Dental amalgam is a mixture of mercury, silver, tin and copper. Mercury, which makes up about 50% of the compound, binds the metals together to provide a strong, durable filling.
Posted by Khushi 💕 2 hours ago
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Posted by Prince Nishad 2 hours ago
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Gaurav Seth an hour ago
Alloys are homogeneous mixtures of two or more metals or a metal and a non metal.
They are prepared in the following ways:
(i) Melting the primary metal.
(ii) Dissolving the other elements in a definite proportion and then cooling them to room temperature.
Constituents and uses of the alloys are:
1. Brass: It is an alloy of copper and zinc
Uses: In making utensils and scientific instruments.
2. Bronze: It is an alloy of copper and tin
Uses: In making statues and medals.
3. Solder: It is an alloy of lead and tin
4. Stainless steel: alloy of Iron
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Yogita Ingle 2 hours ago
The exchange of gases occurs as a result of diffusion down a concentration gradient. Gas molecules move from a region in which they are at high concentration to one in which they are at low concentration. Pulmonary ventilation provides air to the alveoli for this gas exchange process. At the respiratory membrane, where the alveolar and capillary walls meet, gases move across the membranes, with oxygen entering the bloodstream and carbon dioxide exiting. That is, oxygen moves into the blood by diffusion and combines with the haemoglobin in red blood cells to form oxyhaemoglobin.
Posted by Bhagirathi Suna 2 hours ago
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Yogita Ingle 2 hours ago
- Pepsin is an enzyme which acts only in acidic medium. Trypsine is an enzyme which acts in alkaline medium.
- Pepsin is secreted by gastric juice. Trypsin secreted by pancreatic juice.
- Pepsin is secreted in stomach, Trypsin is secreted in small intestine.
- Pepsin is situated in gastric glands, Trypsin is situated in pancreas
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Posted by Tanya Chawla 2 hours ago
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Gaurav Seth an hour ago
Wearing a face mask or other covering over the mouth and nose reduces the forward distance traveled by an exhaled breath by more than 90 percent.
face masks combined with other preventive measures, such as frequent hand-washing and social distancing, help slow the spread of the disease.
Ashwin Gupta 2 hours ago
Posted by Prince Nishad 2 hours ago
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Gaurav Seth an hour ago
(i) Extraction of copper metal - Copper glance (Cu2S):
1. Concentration of the ore (removal of unwanted metals and gangue to purify the ore) is done by Froth floatation method as it is a sulphide ore.
2. Roasting: Copper glance (Cu2S) is roasted in the presence of air. Roasting turns copper glance (ore of copper) into copper (I) oxide.
3. Reduction: Copper oxide is then heated in the absence of air. This reduces copper (I) oxide into copper metal.
4. Refining impure metal: The reduced metal is purified by electrolytic refining method.
Electrolysis of copper from copper sulphate solution (electrolyte) is done using copper electrodes. The crude copper serves as anode while a thin sheet of pure copper serves as cathode.
The electrolyte consists of an acidic solution of CuSO4. Applying suitable voltage to the electrodes causes,
oxidation of copper metal at the anode (Cu -----> Cu2+ + 2e) and
reduction of Cu2+ to form copper metal at the cathode (Cu2+ + 2e -------> Cu).
As the anodes (impure copper) dissolve away, the cathodes on which the pure metal is deposited grow in size.
The impurities in the copper anode which are more active than copper are readily oxidized at the anode but do not plate out at the cathode because their reduction potentials are more negative than that for Cu2+.
Posted by Akshat Kashyap 3 hours ago
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Yogita Ingle 2 hours ago
Metal carbonates and Metal Hydrogencarbonates reacts with acids and produces corresponding metal salt, carbon dioxide and water.
Let us consider the reaction of sodium carbonate with dilute HCl. The reaction proceeds in the following manner.
Na2CO3 + 2HCl → 2NaCl + H2O + CO2
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Sana(Silent Love).. 😘😘 3 hours ago
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Yogita Ingle 6 hours ago
Atomic number of Sodium (Na) – 11
Electronic configuration of Sodium – 1s2 2s2 2p6 3s1
It has one valence electron, it will lose one electron to get octet configuration
Atomic number of Oxygen (O) – 8
Electronic configuration of Oxygen – 1s2 2s2 2p4
It is two electrons short of octet configuration, thus it will gain two electrons.
During the bond formation between Sodium and Oxygen, two Sodium atoms loses one electron each to Oxygen atom.
2 Na -2e- → 2Na+
O + 2e- → O-2
2Na+ + O-2 → Na2O
Atomic number of Magnesium (Mg) – 12
Electronic configuration of Magnesium – 1s2 2s2 2p6 3s2
It has two valence electrons, it will lose two electrons to get octet configuration
Atomic number of Oxygen (O) – 8
Electronic configuration of Oxygen – 1s2 2s2 2p4
It is two electrons short of octet configuration, thus it will gain two electrons.
During the bond formation between Magnesium and Oxygen, one Magnesium atom loses two electrons to Oxygen atom.
Mg -1e- → Mg2+
O + 2e- → O-2
Mg+2 + O-2 → MgO
Posted by Vanshika Singh 8 hours ago
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Gaurav Seth 7 hours ago
They are analogus because they have different structure i.e. humans have complete eye but planaria only have light detcting spots but they perform the same function of seeing
Posted by Priyanshu Kumar 9 hours ago
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Srishti Gupta 7 hours ago
Gaurav Seth 9 hours ago
- A spherical mirror, whose reflecting surface is curved inwards, i.e. faces towards the centre of the sphere, is called a concave mirror.
Posted by Bharat Kol 10 hours ago
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Gaurav Seth 9 hours ago
CONCAVE MIRRORS;
1. They always produce real and inverted images except when an object is placed between the mirror pole and the focus which gives erect virtual images. (for real objects)
2. They produce magnified, diminished and same size images.
3.A parallel beam of incident light is concentrated on its focus and thus such a mirror is called a convergent mirror. Also a light source placed at the focus produces a parallel light beam.
4.Sign convention: The focal length and radius of curvature are taken as negative.
Posted by Surya 10 hours ago
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