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D is the right answer

iv) of these , because eletron rotates and follow a circular path around the nucleus

here, the atomic no is 4 and atomic weight is 9 so, the element is beryllium.hence, the symbol of beryllium is 'be'.

4Be9 is the right answer

c is your correct answer because third element in periodic table

left side of each option is atomic no and after the letter in the option mass no so answer is 4B9

( c) 4 Be9 is the correct answer because atomic number of element is written downside and atomic weight is written up side

option (d) is correctBeryllium has atomic no. 4 and mass no is 9

Saliva contains an enzyme called as Amylase which breaks down the amylose in starch into amylopectin. Amylase causes hydrolysis reaction and breaks down the starch particles into smaller particles, leading to the final production of simple carbohydrates likemaltose, maltotriose, and dextrins.

Experiment to show the effect of saliva on starch:-

1. 2 test tubes labeled A and B are taken, where tube A contains 1 tsp of boiled rice and tube B has 1 tspof rice which has been chewed for 3-5 mins.

2. 4 ml water is added to both the test tubes and then 2-3 drops of iodine solution is also added to each test tube.The color in the tube A changes to bluish-black color, whereas the color in the tube B remains unchanged.

This is because the rice in the tube B has been chewed and the saliva has acted on it and broken down the starch molecules into smaller sugar particles. But, the starch in the tube A was not chewed so the starch molecules are intact in it. The starch reacts with the iodine to give a bluish-black color. This indicates the action of saliva on starch.

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It is because Ammonia (NH3) can create hydrogen bonds whereas Phosphine (PH3) cannot. ... So hydrogen bonding in ammonia is much more stronger than phosphine. More the intermolecular force more Will be the boiling point. So NH3has higher boiling point.

Ironplays an importantrolein the transfer of oxygen by the cytochrome, molecule involved in energy production.

Valence shell electronic configuration of Na is 3s1 and of Mg is 3s2The first electron is to be removed from ha;lf filled 3s orbital of Na which is more easy as compare to the removal of one electron from fully filled stable 2s orbital of Mg. So,first ionization enthalpy of sodium is lower than that of magnesium .The 2ndelectron is to be removed from fully filled 2p orbital of Na+ which requires extra energy as compare to removal of electron from half filled 2s orbital of Mg+.So,second ionization enthalpy of Na is higher than that of magnesium.

6×(sp2)C−Csigma(σ)bonds

6×(sp2)C−Hsigma(σ)bonds

3×(sp2)C=Cpi(π)bonds

Total sigma bonds are 12 and total pi bonds are 3

(A) is correct option

Both carbon and oxygen bonds in carbon dioxide are COVALENT in nature. A covalent bond is formed when two non-metal atoms share a pair of electrons. Here both carbon and oxygen are non-metals.

because of electronegativity of Fluorine atom. It attracts all the electrons cloud towards itself , Thus repels oxygen from both side, so the bond length between O-O gets reduced.

Molarity = Number of moles / Amount of solution ( In litres )

NaOH molar mass = 23 + 16 + 1 = 40 g

=> Number of moles in 4 g = 4 g / 40 g = 0.1 mole

Amount of water = 0.5 litres

Molarity = 0.1 Mole / 0.5 Litres

=> Molarity = 0.2 M

Nissil granules are found in neurons and they form the basis of protein synthesis. These granules are composed of endoplasmic reticulum.

1is the answer of this question

1 is right answer of this question

1 is the correct answer of the given question

1 is the correct answer of this question

Rutherford's model of the atom described a dense, heavy, positively charged nucleus surrounded by negative electrons that balance out the charge of the atom. He also concluded that the atom is mostly made up of empty space.

Rutherford wanted to test the accepted theory of his day proposed by JJ Thompson where the atom was considered a round mass made of negative and positive charged particles all mixed together, called a plum pudding model.

He bombarded a thin sheet of gold with positively charged particles (alpha particles were used) to see if they would pass straight through the foil as expected. However some particles bounced back from the foil or passed through at an angle (were deflected), suggesting the gold atoms were not a homogeneous mix of positive and negative.

The following are the drawbacksof Rutherford atomic model.1) inability to explain the stabilityof atom2) inability to explain the concept of electronic configuration and energy levels of shell3) inability to explain the properties of atoms to form molecule.

Equilibrium constant does not depend on pressure it only depends on temperature so it will remain unchanged

why you do not send my answer i asked aquestion 2 November

The beam of rays which travel in a direction away from anode towards cathode when a gas taken in a discharge tube is subjected to the action of high voltage under low pressure are known as canal rays. It is also called anode rays. It was discovered by E. Goldstein in 1886.

Solidsarerigidbecause the intermolecular forces of attraction that are present insolidsare very strong. The constituent particles ofsolidscannot move from their positions they can only vibrate from their mean positive.

An atomic mass unit (symbolized AMU or amu) is defined as precisely 1/12 the mass of an atom of carbon-12. The carbon-12 (C-12) atom has six protons and six neutrons in its nucleus. In imprecise terms, one AMU is the average of the proton rest mass and the neutron rest mass

option (a)

option (3) is correct.

1.9858 is the value of gas constant in the given units

electron,proton and neutron are the three sub atomic particles of an atom

electron ,proton and neutron are the fundamental(sub atomic) particles of an atom

The three sub-atomic particles of an atom are electrons, protons and neutrons.

Ionic solids, which haveanionicvacancies due to metal excess defect, develop colour. The colour develops because of the presence ofelectronsin theanionicsites. Theseelectronsabsorb energy from the visible part of radiation and get excited.

spontaneous

spontaneous

TheSIderivedunit of thermal conductivityis watt per metre kelvinCGS= Centimetre–gram–second system of units. ... The centimetre–gram–second system of units is a variant of the metric system based on the centimetre as the unit of length, the gram as the unit of mass, and the second as the unit of time.

option d is the correct answer of the given question

Option (d) is the correct answer(d). of the above.

Q=mL+mcΔt+mL'

=10*80+10*1*(100-0)+10*540

=800+1000+5400

=7200cal.=7.2kcal

L=heat of fusion of ice

L'=heat of vapourisation of water

Neon +3S2+3P2= SILICONVALENCE ELECTRON =4

required number of Valence Electrons is equal to 2 + 2 is equal to 4

total no of electron = =2+2+6+2+2 =141st orbit contain maximum electron = 22nd orbit contain maximum electron = 8in 3rd orbit = 4we know that uttermost electron is called valence electron 2 , 8 , 4here 4 is the outermost electron so valence electron is 4.

4 is the correct answer of the given question.

To form a cyclone, warm, moist air over the ocean rises upward from near the surface. As this air moves up and away from the ocean surface, it leaves is less air near the surface. So basically as the warm air rises, it causes an area of lower air pressure below.

•Air from surrounding areas with higher air pressure pushes in to the low pressure area. Then this new “cool” air becomes warm and moist and rises, too. And the cycle continues…

•As the warmed, moist air rises and cools the water in the air forms clouds. The whole system of clouds and wind spins and grows, fed by the ocean’s heat and water evaporating from the ocean surface.

•As the storm system rotates faster and faster, an eye forms in the centre. It is very calm and clear in the eye, with very low air pressure. Higher pressure air from above flows down into the eye.

Investors usedurationto predict bond pricechanges.Durationis a measure of a bond's interest rate risk. It is the weighted average of the time periods until a bond or bond portfolio's interest and principal payments are received, and it's expressed in years.

which is not a matter ?m.c.q. option air , smell , chair , cold drink correct option

As H2 is there on RHShence2H+ requiredhence value of X will be 2

Unbalanced equation is:Al + H⁺ ––––––> Al³⁺ + H₂

This can be divided into two parts:Al ––––––> Al³⁺ + 3e⁻ ––– (1)2H⁺ + 2e⁻ ––––––> H₂ ––– (2)

Since no. of electrons for a reaction are fixed, so multiply eqn. (1) × 2 and eqn. (2) ×3. Add both the resultant eqns.:

2Al + 6H⁺ ––––––> 2Al³⁺ + 3H₂

This is the balanced equation. And, it can be seen that the value of x is 6. ∴ The correct answer is (3) 6.

Ammonia is a strong colourless gas. It has strong and irritating smell. It creates irritating atmosphere with its smell. Even it is spilled at the corner of room it can diffuse to whole room fastly. So the students felt irritating and unpleasant smell.