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Leadis more stable invalency2 than 4. Hence,leadshowsthe valencyof 2. The s electrons of the elements down the group cannot participate in chemical reactions because of the powerful nuclear attraction. SoPb exhibits +2 oxidation state rather than +4.Hence, option (A) is correct.

Before he kills King Duncan, Macbeth is apprehensive about the idea of murder. Immediately after the killing, Macbeth is haunted by intense guilt; he is hallucinating voices, and he fears that he is cursed never to sleep again. After the first murder, though, Macbeth's reservations about killing seem to become fewer and fewer. He orders the killings of Banquo and his son, and of Macduff's family, with apparent ease—he doesn't seem to feel guilty anymore. He has become a fierce tyrant.

1. Particles of matter are very tiny in size.2. They have spaces between them.3. Particles of matter move constantly.4. They are attracted towards each other.

Law of octaves, inchemistry, the generalization made by the English chemist J.A.R.Newlands in 1865 that, if the chemical elements are arranged according to increasingatomic weight, those with similar physical and chemical properties occur after each interval of seven elements. Newlands was one of the first to detect a periodic pattern in the properties of the elements and anticipated later developments of the periodic law.

Newland's octave is a periodic table which are arranged the known elements by its atomic weight. The last element of that periodic table is Thorium.

Limitations of newlands law of octaves qre:

1) Newlands assumed that only 56 elements existed in nature and no more elements would be further discovered in the nearer future. But later on several new elements were discovered, whose properties couldn’t be defined as per the Law of Octaves.

2)In order to fit elements into law of octaves Newlands not only adjusted two elementsin the same slot but also adjusted some unlike elements under the same note.

3)Cobalt and nickel are in the same slot and are positioned in the same column with fluorine, chlorine and bromine possessing different properties than these elements.

4)Iron possessing similar properties as cobalt and nickel, is placed far away from these elements.

5) Thus, Newlands’ Law of Octaves can be obeyed well by the lighter elements only.

This law states that "when the elements are arranged in order of increasing atomic mass thn property of eighth element are similar to the first."

Limitations of Newlands’ law of octaves:a)It was not applicable throughout the arrangements. It was applicable up to calcium only. Theproperties of the elements listed after calcium showed no resemblance to the properties of the elements above them.b)Those elements that were discovered afterNewlands’ octaves did not follow the law of octaves.c)Theposition of cobalt and nickel in the groupof the elements (F, Cl) of different properties could not be explained.d)Placing of iron far away from cobalt and nickel, which have similar properties as iron, could also not be explained

Ans :- 92 elements

It used to be believed that of the first92 elementson the periodic table (1 is hydrogen and92is uranium) that90 elementsoccur naturally. Technetium (atomic number43) and promethium (atomic number 61) were synthesized by man before they were identified in nature.

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one hundred and eighteen

the periodic table has118confirmed elements, from element 1 (hydrogen) to118(oganesson)

how many elements are there in periodic table by mandeleev??? also name of first and last element?

plz response to the questions

Antacids are mild alkalides. There are used for getting relief from acidity and indigestion and sometimes even headache. When taken orally, it reacts with hy¬drochloric acid present in the stomach and reduces its strength by consuming some of it. Ex : Milk of Magnesia.

d. isotopes

Explanation:Most elements as they occur naturally on earth are mixtures of several isotopes.

For example:* The element hydrogen has atoms that have one proton in the nucleus. This is the most common form of hydrogen. They have an atomic number of one due to the presence of single proton in the nucleus, and a mass of one due to the presence of a single proton.

* Occasionally, one finds an atom of hydrogen in which a neutron has been incorporated into the nucleus. This isotope of hydrogen is characterized by an atomic number of one (only one proton; hydrogen can only have one proton in the nucleus), but an atomic mass of two (one proton plus one neutron). This isotope of hydrogen is known as "deuterium" or heavy hydrogen.

* Finally, even rarer is the third isotope of hydrogen [3H]. It has a mass of three which can only occur from the presence of two neutrons in the nucleus. This final isotope of hydrogen is known as "tritium" and it is radioactive.

Group 16 elementsare: naturally occurring oxygen, sulfur, selenium, tellurium, polonium, and the man-madeelementlivermorium. The atoms ofGroup 16 elementshave 6 valence electrons. ... Bondsbetweenhydrogen andGroup 16atoms are covalent so thehydrides of Group 16 elementsare covalent molecules.

among this Sf6 is almost neutral

a) artificial or man-made fibres.

artificial

Nucleus and cytoplasm and plasma membrane

Stain will be iodine

cation - Mg2+

anoin - CH3COO-

Molecular mass of CO2 = 44 g

1 Mol CO2 occupies 22.4l

ie, 44 g CO2 = 22.4 l

so, 4.4 CO2 ( 44 * 0.1 =4.4 ) = 22.4 * 0.1

=2.24 L

1 mole each substance contains Avogadro number (NA) moleculesMolar mass of butane is = 12X4 + 1X10 = 58So 58 g contains NAMolecules = 14 NAatoms1 g water contains 14/58 NAatoms = 0.24 NAatomsMolar mass of nitrogen is = 14X2 = 28So 28 g contains NAMolecules = 2 NAatoms1 g water contains 2/28 NAatoms = 0.07 NAatomsMolar mass of silver is = 108So 108 g contains NAatoms1 g water contains 1/108 NAatoms = 0.0093 NAatomsMolar mass of water is = 1X2 + 16 = 18So 18 g contains NAMolecules = 3 NAatoms1 g water contains 3/18 NAatoms = 0.17 NAatomsSo 1 g butane have highest number of atoms.

Ethanol is alcohol commonly referred to as ethyl alcohol. Ethanol's chemical formula is C2H6O. This chemical formula can also be written as CH3CH2OH or C2H5OH.

Properties:

(i) It is flammable and volatile, so it evaporates easily when left in an open container.

(ii) It has low melting point of -114.5° C which allows it to be used in antifreeze products.

P1V1 / (n1T1) = P2V2 / (n2T2)canceling n...P1V1 / T1 = P2V2 / T2rearranging for V2...V2 = V1 x (P1 / P2) x (T2 / T1)

and solving...V2 = 6.85L x (772 mmHg / 760mmHg) x (273.15K / 308.15K) = 6.17L

thank you

Molecular mass of CO2 = 44 g

1 Mol CO2 occupies 22.4l

ie, 44 g CO2 = 22.4 l

so, 4.4 CO2 ( 44 * 0.1 =4.4 ) = 22.4 * 0.1

=2.24 L

Molar mass at STP

1.25/1L*22.4L=28g

The answer should be N2 gas

Option 4 is correct. Molar conductivity of NaOH is required.

The option is 22.4 cc

Q=ct, 2 × 193 =386 c,96500 c liberates 5600 cc of oxygen,Therefore 386 liberates 386 × 5600/96500 cc= 22.4 of oxygen

Electrolysis is the process of decomposing the compound into its constituents elements by supplying electricity.Here acidifed water means water is added with few drops of Sulphuric acid to make water a better electrolyte .

Reactions that occur during electrolysis of acidifed water are:1 At cathode hydrogen gas is released. H+ ions are attracted towards cathode electrode and convert as hydrogen gas.

2H+ + 2e ---> H2 gas.

2. At Anode, oxygen gas is evolved.

overall reaction:.electricity 2H20 ------------------->2H2 + O2

hence helium and neon can exist only as monoatomic species

When ethyne is burnt in air incomplete burning takes place and produce sooty flame due to limited supply oxygen present in the air. However, if ethyne is burnt in oxygen, it gives a cleanflame with high temperature (3000°C ) due to complete combustion of ethyne. Hence, This oxy-acetyleneflame is used for welding and it is not possible to attain such a high temperature with air. Due this reason a mixture of ethyne and air is not used for welding.

tnx

It has approximately the same amount of ionic and covalent character making it amphoteric and thus reacting with both Acids such as HCl and Bases such as NaOH.]

Aluminiumoxideis anamphotericsubstance, meaning it can react with both acids and bases, such as hydrofluoric acid and sodium hydroxide, acting as an acid with a base and a base with an acid, neutralising the other and producing a salt.

Chromosomes are thread-like structures in which DNA is tightly packaged within the nucleus. DNA is coiled around proteins called histones, which provide the structural support.

To find the titre value we can take average of three different values obtained from different burettes.Titre value = (25.2 + 25.25 + 25.0)/3 = 25.15 mL

The answer should be expressed in least significant figure as in one of the value. Since least significant figure is 3. So the answer is 25.1 mL

potassium chloride and sodium chloride are crystalline substance which donot contain water of crystallization

Let us compute the molar mass of the molecule first

Mass of Al = 27 AMUMass of O = 16 AMUSo mass of Al2O3 "molecule" = 2x27 + 3x16 = 102 AMU

So 1 mole of ALUMINIUM OXIDE will weigh 102 g1 mole of any pure substance contains Avogrado's number of molecules, that is 6.023x10^23.Thus 0.051g of ALUMINIUM OXIDE will contain 6.023x(10^23)x.051/102 = 6.023x(10^20)/2 "molecules "

Each molecule contains two ions of aluminium.

So total no. Of ions in the given amount of substance = 2x6.023x(10^20)/2 =6.023x10^20

a)H2+O2------2H2O this is the right answer

This is because the valency of iron in ferric chloride is 3+, whereas that of potassium in KCl is 1+. The higher the valency, the better is the coagulation efficiency of the compound. Also, ferric chloride is more compatible with skin than KCl. Thus, FeCl3 does not cause any irritation when applied overwound.

This is because the valency of iron in ferric chloride is 3+, whereas that of potassium in KCl is 1+. The higher the valency, the better is the coagulation efficiency of the compound. Also, ferric chloride is more compatible with skin than KCl. Thus,FeCl3FeCl3does not cause any irritation when applied over wound.

a)Ans: Atomic number of Sodium (Na) – 11Electronic configuration of Sodium – 1s22s22p63s1It has one valence electron, it will lose one electron to get octet configurationAtomic number of Oxygen (O) – 8Electronic configuration of Oxygen – 1s22s22p4It 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-22Na++ O-2→ Na2OAtomic number of Magnesium (Mg) – 12Electronic configuration of Magnesium – 1s22s22p63s2It has two valence electrons, it will lose two electrons to get octet configurationAtomic number of Oxygen (O) – 8Electronic configuration of Oxygen – 1s22s22p4It 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-2Mg+2+ O-2→ MgO

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Anisotonic solutionhas the same solute concentration as the fluid inside a cell. Ahypotonic solutionhas a lower solute concentration than the fluid inside a cell. Ahypertonic solutionhas a higher solute concentration than the fluid inside a cell.

Hypertonicrefers to a greater concentration. In biology, ahypertonic solutionis one with a higher concentration of solutes outsidethecell than insidethecell. ...Hypotonicrefers to a lesser concentration. In biology, ahypotonic solutionhas a lower concentration of solutes outsidethecell than insidethecell

Hypertonicrefers to a greater concentration. In biology, ahypertonic solutionis one with a higher concentrationofsolutes outside the cell than inside the cell. ...Hypotonicrefers to a lesser concentration. In biology, ahypotonic solutionhas a lower concentrationofsolutes outside the cell than inside the cell.

When we use these terms, we are considering only solutes that cannot cross the membrane.

If the extracellular fluid has lower osmolarity than the fluid inside the cell, it’s said to behypotonic—hypomeans less than—to the cell, and the net flow of water will be into the cell.

In the reverse case, if the extracellular fluid has a higher osmolarity than the cell’s cytoplasm, it’s said to behypertonic—hypermeans greater than—to the cell, and water will move out of the cell to the region of higher solute concentration.

In anisotonicsolution—isomeans the same—the extracellular fluid has the same osmolarity as the cell, and there will be no net movement of water into or out of the cell.

Irish x to by hi to ml on y u have to do it in in a new job in London on a daily rate is about

ahypotonic is the correct answer

In cold and temperate countries winter temperatures can drop low enough to freeze the water in a car's cooling system which results in blockage, overheating and engine damage. The usual antifreeze additive is ethylene glycol also known as ethane diol, not alcohol. This lowers the freezing point of the cooling liquid to a safe level. 30% antifreeze gives protection down to about -10deg but for extreme conditions 100% ethylene glycol can be used.

This is an oxidation-reduction (redox) reaction:

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