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Any material starts burning when it’s temperature reaches a fixed value. The temperature at which the material starts burning is called ignition point. This value is different for different materials.

If heat is supplied to a material, it’s temperature increased. But if it is taken away at the same time the material temperature does not increase or increases very slowly.

When a paper cup is heated and there is water in it, the heat received by the material of the cup is transferred to the water inside. Thus the material of the cup and the water in it get heated simultaneously. If the ignition point of the paper is greater than the boiling point of water, water boils and the paper cup does not get ignited.

a.He shifts the pHof thefresh milk from 6toalkalineso that in basic formitwill not spoil easily. b Thismilktakes a long time to set as curd because the lactic acid produced reacts with the baking soda

Yes, displacement reaction is also a redox reaction. The element getting displaced undergoes reduction and the reactive metal gets oxidised.

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Redox is a chemical reaction in which the oxidation states of atoms are changed. Any such reaction involves both a reduction process and a complementary oxidation process, two key concepts involved with electron transfer processes

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H+ is not an electrophile

If the pH of a solution is less than 7, the solution is called acidic

pH value of an acid is less then 7

An acid will always below PH7 if it is more then PH7 then it is a base or weak acid

ph value of an acid is less then 7 but more than 7 is called base and equel 7 is called neutral

Chlorine gas reacts with lime water to form calcium oxychloride that is bleaching powder. The chemical reaction is as follows -2Ca(OH)2 + 2Cl2 → Ca(OCl)2 + CaCl2 + 2H2O

Increasw its ph by adding NaoHDecrease its pH by adding acid like H2SO4 or HCl

The pH of solution which liberate CO2 from Na2CO3 should be less than 7 as acid can do this.The Balanced chemical equation is:Na2CO3 + 2HCl ----->2NaCl+ H2O+CO2As salt and water is formed hence it is neautrilization reaction

pH of a solution is given by the following relation

pH = -log[H+]

Thus, more is the H+ion concentration of a solution, lower is the pH and vice-versa. Hence, increase in the H+ion concentration of a solution increases the acidic strength of the solution and lowers its pH.

pH is a quantitative measure of the acidity or the basicity of an aqueous solution this is because in an acidic environment the hydrogen ions are thoroughly present whereas in a basic environment the hydrogen ions are scarcely present.

list of base and acid with ph value plese

pH of 7 is neutralpH less than 7 is acidic.pH more than 7 is basic.

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We should take a base such as a antacid tablet or milk of magnesia because it neutralises the effect of acid.

Theacidity of phenolsis due to its ability to lose hydrogen ion to form phenoxide ions.In aphenolmolecule, the sp2 hybridised carbon atom of benzene ring attached directly to the hydroxyl group acts as an electron withdrawing group. Thus, the phenoxide ion is formed

Acidity of base is defined as the number of ionizable hydrogen ions (OH-) present in one molecule of a base is called acidity.

Versatile nature of carbon

The versatile nature of carbon due to the presence of covalent bond enables it to form a large number of compounds.

(i) Carbon due to its property of catenation possesses a unique ability to form bonds with other atoms of carbon, giving rise to large number of molecules and compounds having long chains of carbon, branched chains of carbon or carbon atoms arranged in rings and linked by single, double or triple bonds.(ii) Carbon being tetravalent is capable of bonding with four other atoms of carbon or any other combining mono-valent element.

(iii) Carbon forms compounds with oxygen (Carbon-dioxide), hydrogen (Methane), nitrogen (Hydrogen cyanide), sulphur, chlorine (Chloromethane) and many other elements giving rise to compounds with specific properties depending upon the elements present in the compound.

For decreasing acidity we take Antacid.Because antacid contains base which react with acid present in our body and form salt and water and it help to get relief from acidity.

the negative value of logithem to the base 10of hydrogen concentration is called pH

importance of ph:

generally different soil have different type of pH based on pH value of soil , different crops are suggested

pH in digestive system:in our stomach hostomin enzyme produce too much of acid and this cause pain and irritation to get rid of this pain people use antacids

Answer:

i)Measure H+ concentration ii)Measure OH- concentration

Explanation:

SincepHis basically the number of H+ ions in a solution, that's what you're trying to find. (it's actually -log of H+, which is irrelevant since this is a conceptual question). You can do this with a variety of chemicals.And pOH is always 14-pH. So you can also use the number of OH- ions to find pOH, which can find pH.

NH4cl is the correct answer of the given question

NH4CL is the right answer of your question.

NH4Cl - Ammonium Chloride. This is a salt that issolublein water, but also sublimes as a solid.

NH4Cl sublimes as a solid

ammonium chloride-NH4CL that is answer to your question

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In chemistry,orbital hybridisation(orhybridization) is the concept of mixingatomic orbitalsinto new hybridorbitals(with different energies, shapes, etc., than the componentatomic orbitals) suitable for the pairing of electrons to form chemical bonds in valence bond theory.

Hybridization is defined as an intermixing of a set of atomic orbitals of slightly different energies, thereby forming a new set of orbitals having equivalent energies and shapes. For example, one 2s-orbital hybridizes with two 2p-orbitals of carbon to form three new sp2 hybrid orbitals. These hybrid orbitals have minimum repulsion between their electron pairs and thus, are more stable. Hybridization helps indicate the geometry of the molecule. Shape of sp hybrid orbitals: sp hybrid orbitals have a linear shape. They are formed by the intermixing of s and p orbitals as ÷

In chemistry,orbital hybridisation(orhybridization) is the concept of mixingatomic orbitalsinto new hybridorbitals(with different energies, shapes, etc., than the componentatomic orbitals) suitable for the pairing of electrons to form chemical bonds in valence bond theory.Hybridizationisdefinedas an intermixing of a set ofatomic orbitalsof slightly different energies, thereby forming a new set oforbitalshaving equivalent energies andshapes. For example, one 2s-orbitalhybridizes with two 2p-orbitalsof carbon to form three newsp2 hybrid orbitals.

hybridization of atomic orbitals is a process of intermixing new orbitals into new hybrid orbitals without changing the internal energy of an atom

Hybridization is defined as an intermixing of a set of atomic orbitals of slightly different energies, thereby forming a new set of orbitals having equivalent energies and shapes. For example, one 2s-orbital hybridizes with two 2p-orbitals of carbon to form three new sp2 hybrid orbitals. These hybrid orbitals have minimum repulsion between their electron pairs and thus, are more stable. Hybridization helps indicate the geometry of the molecule. Shape of sp hybrid orbitals: sp hybrid orbitals have a linear shape. They are formed by the intermixing of s and p orbitals as: Read more on Sarthaks.com - https://www.sarthaks.com/8329/what-meant-by-hybridisation-atomic-orbitals-describe-the-shapes-sp2-sp3-hybrid-orbitals

Talking about carbon, it can hybridize on three different ways, because his valence shell orbitals allows him to do so. He can hybridize (mix) his valence orbitals to generate sets of equivalent sp,sp2 or sp3 orbitals.That’s the only requirement that you have in other to mix molecular orbitals into hybridized ones. And this doesn’t applies only to carbon (for example, oxygen is sp3 hybridized in ethanol, sp2 hybridized in ketones, and sp hybridized in carbon monoxide)

The strength of bonds formed by overlap ofsp3−sp3sp3−sp3bond is more because these orbitals have more directional character.

Hence ( s-s) is the correct answer.

thelawthat the properties of the elements areperiodicfunctions of their atomic numbers. Also called Mendeleev'slaw. (originally) the statement that the chemical and physical properties of the elements recur periodically when the elements are arranged in the order of their atomic weights.

the electron affinity of an atom or molecule is defined as the amount of energy released or spent when an electron is added to a neutral atom or molecule in the gaseous state to form a negative ion

Fluorine, thoughhigher than chlorinein the periodic table, has a very small atomic size. This makes the fluoride anion so formed unstable (highly reactive) due to a very high charge/mass ratio. ... As a result,fluorinehas anelectron affinitylessthanthat ofchlorine

option 3 , should be correct , because it will dissociate into 4 ions.

Cl>F>Br>IAs the size of Fluorine is smaller electron repelsion is moreand in Br and I, nuclear influence is less

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HCl is a strong acid and its salt do not form bufter solution. As the resultant solution is acidic, hence pH is less than 7.

(Ph)3C• > (Ph)2HC• > (Ph)H2C•

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According to Bohr Atomic model, a small positively charged nucleus is surrounded by revolving negatively charged electrons in fixed orbits. He concluded that electron will have more energy if it is located away from the nucleus whereas the electrons will have less energy if it located near the nucleus.

Limitations of BohrAtomic Model Theory:

1.It violates theHeisenberg Uncertainty Principle. The Bohr atomic model theory considers electrons to have both a known radius and orbit i.e. known position and momentum at the same time, which is impossible according to Heisenberg.

2.The Bohr atomic model theory made correct predictions for smaller sized atoms like hydrogen, butpoor spectral predictions are obtained when larger atoms are considered.

3.It failed to explain the Zeeman effect when the spectral line is split into several components in the presence of a magnetic field.

4.It failed to explain the Stark effect when the spectral line gets split up into fine lines in the presence of an electric field

As before, Rutherford atomic model was also challenged and questioned by many. Rutherford atomic model failed to explain about the stability of electrons in a circular path.

As per Rutherford’s model, electrons revolve around the nucleus in a circular path. But particles that are in motion on a circular path would undergo acceleration, and acceleration causes radiation of energy by charged particles. Eventually, electrons should lose energy and fall into the nucleus. And this points to the instability of atom. But this is not possible because atoms are stable. Hence, Rutherford failed to give an explanation on account of this

In chemistry, the molar mass M is a physical property defined as the mass of a given substance divided by the amount of substance. The base SI unit for molar mass is kg/mol. However, for historical reasons, molar masses are almost always expressed in g/mol. As an example, the molar mass of water: M ≈ 18.015 g/mol.

it is a physical property defined as the mass of a given substance divided by the amount of substance

Postulates of Dalton’s Atomic Theory

The matter is made up of indivisible particles known as atoms.

The properties of all the atoms of a given element are the same including mass. This can also be stated as all the atoms of an element have identical mass while the atoms of different elements have different masses.

Atoms of different elements combine in fixed ratios to form compounds.

Atoms are neither created nor destroyed. This implies that during chemical reactions, no atoms are created nor destroyed.

The formation of new products (compounds) results from the rearrangement of existing atoms (reactants).

Atoms of an element are identical inmass, size and many other chemical or physical properties, but atoms of two-different elements differ in mass, size, and many other chemical or physical properties.

Dalton's atomic theory proposed that allmatterwas composed of atoms, indivisible andindestructiblebuilding blocks. While all atoms of an element wereidentical,differentelements had atoms of differing size and mass.

Dalton’s atomic theory proposed that all matter was composed of atoms, indivisible and indestructible building blocks. While all atoms of an element were identical, different elements had atoms of differing size and mass.

Dalton’s atomic theory also stated that all compounds were composed of combinations of these atoms in defined ratios.

Dalton also postulated that chemical reactions resulted in the rearrangement of the reacting atoms.

He states that

Everything is made of indivisible atoms.

Atoms within an element are unique.

Compoundsare made of two or more differentelements/ kinds of atom.

Chemical reactions are rearrangements of atoms.

He assumed that atoms are indivisible,

Molar mass of:Hydrogen = 1.008Oxygen = 15.9994Molar mass of H2O= (2×1.008) + 15.9994= 2.016 + 15.9994= 18.0154

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The molar mass is the mass of one mole (or 6.023 X 10^23) particles of that substance. The molar mass of a substance is numerically equal to the atomic mass or the molecular mass of the substance in ‘u’ and is always expressed in grams (or sometimes Kg).

i) Center of the atom is positively charged and highly dense which is known as nucleus which made the whole mass of the atom.

(ii) The electrons rotate around the nucleus in well-defined orbits.

(iii) The size of the nucleus (10−15) is very small as compared to size of atom (10−10).

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There were many limitations of Rutherford's atomic model, which were later corrected by Neils Bohr. These are some to name few:-

Rutherford proposed that electrons revolve at a high speed in circular orbits around the positively charged nucleus. When a charged particle i. e. electron revolves around positively charge nucleus, it needs to be accelerated so as to keep it moving in circular orbits. However, according to electromagnetic theory, whenever a charged particle such as an electron is accelerated around another charged center ( nucleus ) which are under force of attraction, there will be continuous radiation of energy. This loss of energy would slow down the speed of the electron. This would reduce the radius of the electron–orbit. Eventually the electron would fall into the nucleus. The result would be that the atom would collapse. But this does not happen. Thus Rutherford’s atom could not explain the stability of the atom.

Rutherford proposed that electrons revolve around the nucleus in the fixed orbits. However, he did not specify the orbits and the number of electrons in each orbit.

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Ans :- Rutherford model and Bohr model are models that explain the structure of anatom. Rutherford model was proposed by Ernest Rutherford in 1911. Bohr model was proposed by Niels Bohr in 1915. Bohr model is considered as a modification of Rutherford model. The main difference between Rutherford and Bohr model is thatRutherford model does not explain the energy levels in an atom whereas Bohr model explains the energy levels in an atom.

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(i)Most of the alpha particles passed through the gold foil without getting deflected.

(ii)Very few particles were deflected from their path by 180o indicating that the whole mass of the atom is present in its centre in a very small volume.

(iii)Few particles were deflected at small angles from their path and very few were deflected from their path by 180o indicating that the positive charge of the atom occupies very little space and is located at the centre.