Design an experiment to demonstrate phototropism.

Answer:

Hindi ko po ma gets sinasabi nyu pwedeng pakiayus

Acids have sour taste, low pH and dissolves metals.

The list that describes the characteristics of an acid is that it has sour taste, low pH, and dissolves metals.

An acid is a chemical substance that has the ability to donate hydrogen ions when involved in a chemical reaction.

The following are the characteristics or features of an acid:

Therefore, the list that describes the characteristics of an acid is that it has sour taste, low pH, and dissolves metals.

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Answer:

Te

K

Explanation:

Main group elements are elements designated and located on the s-block and p-block on the periodic table. The core group or prominent elements are the elements that make up those groups. These groupings comprise the most naturally rich and abundant elements. The main group elements are those whose characteristics are more predicted as a function of their periodic table location. From the given options, only Te and K are elements of the main-group.

Answer:

For (1): The correct option is (a)

For (2): The correct option is (a) and 333.6 kJ of heat will be absorbed when 70.9 g of ammonia reacts.

Explanation:

There are 2 types of reactions that are classified based on enthalpy change:

Endothermic reactions: These are the reactions where heat is absorbed by the reaction. The change in enthalpy of the reaction, [tex]\Delta H_{rxn}[/tex] is positive for these reactions.

Exothermic reactions: These are the reactions where heat is released by the reaction. The change in enthalpy of the reaction, [tex]\Delta H_{rxn}[/tex] is negative for these reactions.

For the given chemical reaction:

[tex]2NH_3(g)\rightarrow N_2(g)+3H_2(g);Delta H=160kJ[/tex]

As the change in enthalpy or heat of the reaction is positive. Thus, the reaction is an endothermic reaction because heat is absorbed by the reaction.

When ammonia reacts, some amount of heat will be absorbed by the reaction. Thus, we can say the heat will be absorbed.

The number of moles is calculated by using the equation:

[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex] ......(1)

Given mass of ammonia = 70.9 g

Molar mass of ammonia = 17 g/mol

Using equation 1:

[tex]\text{Moles of ammonia}=\frac{70.9g}{17g/mol}=4.17mol[/tex]

By stoichiometry of the reaction:

If 2 mole of ammonia reacts, the heat absorbed is 160 kJ

So, if 4.17 moles of ammonia reacts, the heat absorbed will be = [tex]\frac{160kJ}{2mol}\times 4.17mol=333.6kJ[/tex]

Hence, 333.6 kJ of heat will be absorbed when 70.9 g of ammonia reacts

The question is incomplete, the complete question is shown in the image attached to this answer

Answer:

1) K

2) F

3) Si

4) Br

Explanation:

If an element has a more negative value of electron affinity, then it has a greater ability to attract an electron.

In each of the following pairs of elements, one element has a more negative electron affinity for certain reasons.

Between K and Ca, the incoming electron in K goes into a 4s orbital which is lower in energy and more stable. For Ca, the electron goes into a 3d orbital which is more unstable.

Between Ne and F, Ne already has a filled outermost shell hence the incoming electron goes into the higher energy 3s level. In F, the electron goes into the 2p level and completes it. Hence F has a more negative electron affinity.

Let us recall that half filled and completely filled orbitals are exceptionally stable. Hence, the electron affinity of Si is more negative than that of P because in P, the electron goes into an exceptionally stable half filled orbital.

Recall that the more the value of Zeff, the more negative the electron affinity hence electron affinity increases across a period; hence, Br has a more negative value of electron affinity than Se.

Answer:

Molecules of O₂F₂ = mass of O₂F₂ × (1 mole O₂F₂ / 70 g O₂F₂) × (6.02 × 10²³ molecules / one mole of O₂F₂)

Explanation:

The Avogadros constant gives the the number of specified entities in one mole of a substance. One mole of any substance contains 6.02 × 10²³ particles. Therefore, one mole of O₂F₂ contains 6.02 × 10²³ molecules.

Also, the molar mass of a substance is the mass in grams of one mole of that substance. It is obtained by summing the relative atomic masses of all the atoms of the elements in the substance. For O₂F₂, the molar mass = (2 × 16 + 2 × 19) g/mol = 70 g/mol

Converting to molecules of O₂F₂;

To convert from grams of a substance to molecules of that substance, multiply by the ratio of one mole and mass of one mole, and then by the number of molecules per mole.

Molecules of A = mass of A × (1 mole / mass of one mole) × (6.02 × 10²³ molecules / 1 mole)

Therefore,Molecules of O₂F₂ = mass of O₂F₂ × (1 mole O₂F₂ / 70 g O₂F₂) × (6.02 × 10²³ molecules /one mole of O₂F₂)

Saturated fatty acids lack double bonds between the individual carbon atoms, while in unsaturated fatty acids there is at least one double bond in the fatty acid chain. Saturated fats tend to be solid at room temperature and from animal sources, while unsaturated fats are usually liquid and from plant sources.

Answer:

hope it is helpful to you

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Answer:

1 ) Δs ( entropy change for hot block ) = - Q / th  ( -ve shows heat lost to cold block )

Δs ( entropy change for cold block ) = Q / tc

∴ Total Δs = ΔSc + ΔSh

                 = Q/tc - Q/th

2) ΔSdecomposition = Δh / Temp = ( 181.6 * 10^3 / 773 ) = 234.928 J/k

Explanation:

1) To show that heat flows spontaneously from high temperature to low temperature

example :

Pick two(2) solid metal blocks with varying temperatures ( i.e. one solid block is hot and the other solid block is cold )

Place both blocks for time (t ) in an insulated system to reduce heat loss or gain to or from the environment

Check the temperature of both blocks after time ( t ) it will be observed that both blocks will have same temperature after time t ( first law of thermodynamics )

Δs ( entropy change for hot block ) = - Q / th  ( -ve shows heat lost to cold block )

Δs ( entropy change for cold block ) = Q / tc

∴ Total Δs = ΔSc + ΔSh

                 = Q/tc - Q/th

2) Entropy change for Decomposition of mercuric oxide

2HgO (s) → 2Hg(l) + O₂ (g)

Δs = positive

there is transition from solid to liquid and the melting point of mercury ( the point at which reaction will take place ) = 500⁰C

hence ΔSdecomposition = S⁻ Hg  -  S⁻ HgO =

Δh of reaction = 181.6 KJ

Temp = 500 + 273 = 773 k

hence ΔSdecomposition = Δh / Temp = ( 181.6 * 10^3 / 773 ) = 234.928 J/k

answer; 1/ 20_2[2-] +2e - ->0.

Answer:

2.33 mol C

Explanation:

Step 1: Write the balanced generic chemical equation

3 A ⟶ C + 4 D

Step 2: Establish the appropriate molar ratio

According to the balanced equation, the molar ratio of A to C is 3:1.

Step 3: Calculate the number of moles of C produced from 7 moles of A

We will use the previously established molar ratio.

7 mol A × 1 mol C/3 mol A = 2.33 mol C

Answer:

both

Explanation:

A homolytic fission is said to have occurred when the breakage of a bond between two atoms leaves each of the bonding atoms with equal number of electrons. Homolytic fission often results in the creation of radicals.

Since homolytic fission yields two species with equal number of electrons(usually odd number of electrons), the products of such process can not be charged. They can not be nucleophiles because nucleophiles need to possess two electrons which can be shared with another chemical specie.

Sodium metal reacts rapidly with water to form a solution of sodium hydroxide (NaOH) and hydrogen gas (H2). This reaction is exothermic.

Equation:

2Na + 2H²0 --------}- 2NaOH + H²

Answer:

storage solution , deionized water, stabilizes

Explanation:

A pH meter is a scientific device or instrument that is used to measure the pH of a given aqueous solution thereby determining the nature of the solution whether it is acidic or basic or neutral.

While using the pH meter or taking the measurement using the pH meter --

Answer:

2.89x10⁻⁵M = [HPO₄²⁻]

Explanation:

The equilibrium of H3PO4 in water occurs H2PO4-:

H3PO4(aq) + H2O(l) ⇄ H3O⁺(aq) + H2PO4⁻(aq)

pKa = 2.16. And as pKa = -log Ka; Ka = 10^-2.16

Ka = 6.9183x10⁻³ = [H3O⁺] [H2PO4⁻] / [H3PO4]

As both [H3O⁺] and [H2PO4⁻] comes from the same equilibrium,

[H3O⁺]=[H2PO4⁻] :

[H3O⁺] = X

[H2PO4⁻] = X

[H3PO4] = 0.042 - X

Where X is reaction coordinate

Replacing:

6.9183x10⁻³ = [X] [X] / [0.042 - X]

6.9183x10⁻³ = X² / 0.042 - X

2.905686x10⁻⁴ - 6.9183x10⁻³X - X² = 0

Solving for X:

X = -0.02M. False solution. There is no negative concentration.

X = 0.014M. Right solution

[H2PO4⁻] = 0.014M

In the second equilibrium:

H2PO4⁻(aq) + H2O(l) ⇄ HPO4-(aq) + H3O+(aq)

Based on the same principles of the last equilibrium:

pKa2 = 7.21

Ka2 = 6.166x10⁻⁸ = [HPO4-] [H3O+] / [H2PO4⁻]

[HPO4-] = X

[H3O+] = X

[H2PO4⁻] = 0.014M - X

6.166x10⁻⁸ = X² / [0.014M - X]

8.3623x10⁻¹⁰ - 6.166x10⁻⁸X - X² = 0

Solving for X:

X = -0.0000289485. False solution.

X =

Answer:

The correct answer is - no not adhere to the law of mass conservation.

Explanation:

According to the law of mass conservation in an isolated system, the mass can not be created or destroyed and in a chemical or physical change, the mass of products should be always equal to the mass of reactants.

On the basis of the law the mass of the chemical reaction-

Mass of products = mass of reactants

33 g of methane + 289g of oxygen = 189g of carbon dioxide + 30g of water

322g ≠ 219 g

which means this reaction does not adhere to the law of conservation.

Answer:

Identify a process that is NOT reversible.

Melting of snow

baking of bread

deposition of carbon dioxide

freezing water

melting of aluminum

Explanation:

A physical change is the one in which there is a change only in its physical state, color, the appearance of the substance. But the chemical composition of the substance remains unchanged.

It is a temporary change and can be reversed easily.

For example:

melting, freezing, deposition etc.

Baking is a permanent change and the chemical composition of the substance changes.

Hence, among the given options, baking of bread is not a reversible change.

Out of the following all are physical changes except baking of bread and physical changes are reversible so the process  which is not reversible is baking of bread.

Physical changes are defined as changes which affect only the form of a substance but not it's chemical composition. They are used to separate mixtures in to chemical components but cannot be used to separate compounds to simpler compounds.

Physical changes are always reversible using physical means and involve a change in the physical properties.Examples of physical changes include melting,boiling , change in texture, size,color,volume and density.Magnetism, crystallization, formation of alloys are all reversible and hence physical changes.

They involve only rearrangement of atoms and are often characterized to be changes which are reversible.

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Answer:

indicates the number of subshells

Answer:

1.17 L of H₂

Explanation:

We'll begin by calculating the number of mole in 2.3 g of Mg. This can be obtained as follow:

Mass of Mg = 2.3 g

Molar mass of Mg = 24 g/mol

Mole of Mg =?

Mole = mass /molar mass

Mole of Mg = 2.3 / 24

Mole of Mg = 0.096 mole

Next, we shall determine the number of mole of H₂ produced by the reaction of 2.3 g (i.e 0.096 mole) of Mg. This can be obtained as follow:

Mg + 2HCl —> MgCl₂ + H₂

From the balanced equation above,

1 mole of Mg reacted to 1 mole of H₂.

Therefore, 0.096 mole of Mg will also react to produce 0.096 mole of H₂.

Finally, we shall determine volume of H₂ produced from the reaction. This can be obtained as follow:

Number of mole (n) of H₂ = 0.096 mole

Pressure (P) = 2 atm

Temperature (T) = 298 K

Gas constant (R) = 0.0821 atm.L/Kmol

Volume (V) of H₂ =?

PV = nRT

2 × V = 0.096 × 0.0821 × 298

Divide both side by 2

V = (0.096 × 0.0821 × 298) /2

V = 1.17 L

Therefore, 1.17 L of H₂ were obtained from the reaction.

Answer:

Explanation:

1mol of [tex]O_2=2*16{gr\over{mol}}=32{gr\over{mol}}\\\\15.7gr->15.7gr*{1\over{32{gr\over{mol}}}}=0.491mol~of~O_2[/tex]

as 1mol of molecular oxigen reacts with 4 mol of aluminium

1 mol of O2         -----------------------------> 4 mol of Al

0.491 mol of O2  ------------------------------>     x

[tex]x={0.491*4\over{1}}~mol~of~Al=1.9625~mol~of~Al[/tex]

The electronegativity increases across the period and decreases down the group. Thus, option B is correct.

Electronegativity can be defined as the tendency of an atom to gain or attract an electron. The electronegativity has been dependent on the size of the atom, as well as the atomic number and valence electrons.

The atom with the requirement of a less number of atoms to complete its octet can easily gain the electron and thereby have high electronegativity. The atomic size also plays a role in the electronegativity of the atom.

The atom with a bigger size has the lesser force of attraction from the nucleus and thus has difficulty attracting the electron, however, the smaller size atom can easily attract the electron with the attraction force from the nucleus.

Thus, the elements with smaller sizes and a high number of valence electrons are more electronegative. In the periodic table, on moving from left to right the valence electrons increase, thus the electronegativity increases.

On moving down the group, the element size increase, thus the electronegativity decreases down the group.

The electronegativity increases across the period and decreases down the group. Thus, option B is correct.

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Answer:

qualatatiev is fs-hj_jakakak

Answer: A bromine radical is more stable than chlorine radical, so it is less reactive and more choosy.

Explanation:

A chlorine atom being more electronegative in nature is able to attract a hydrogen atom more readily towards itself as compared to a bromine atom.

Since bromine is less electronegative in nature so bromine will be more selective as a hydrogen abstracting agent. As a result, bromine radical is more stable in nature than chlorine radical.

Thus, we can conclude that bromine radical is more stable than chlorine radical, so it is less reactive and more choosy.

Answer:

43.0 L

Explanation:

Step 1: Given and required data

Step 2: Calculate the volume of the flask (V)

We will use the ideal gas equation.

P × V = n × R × T

V = n × R × T / P

V = 1.99 mol × (0.0821 atm.L/mol.K) × 313 K / 1.19 atm = 43.0 L

The answer is 4.30 L

Answer:

don't knoe sorry

Explanation:

The question is incomplete, the complete question is:

A chemist measures the amount of iodine solid produced during an experiment. He finds that 8.31 g of iodine solid is produced. Calculate the number of moles of iodine solid produced. Round your answer to the correct number of significant digits.

Answer: The number of moles of solid iodine produced is 0.0327 moles

Explanation:

The number of moles is defined as the ratio of the mass of a substance to its molar mass.  The equation used is:

[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex] ......(1)

Given mass of solid iodine = 8.31 g

Molar mass of solid iodine = 253.8089 g/mol

Plugging values in equation 1:

[tex]\text{Moles of solid iodine}=\frac{8.31g}{253.8089g/mol}=0.0327mol[/tex]

Hence, the number of moles of solid iodine produced is 0.0327 moles

Answer:

Explanation:

The density of pure water is 1 gram per 1 milliliter or one cubic cm. By knowing the density of water we can use it in dilution equations or to calculate the specific gravity of other solutions.

It can also help us determine what other substances are made of using the water displacement experiment. This is done by observing how much water is displaced when an object is submerged in the water. As long as you know the density of the water, the mass of the object being submerged and the volume of increase you can calculate the density of the object.

This was done by the great Archimedes in discovering what composed the kings crown.

Answer:

The reaction is the combustion of methanol (CH3OH).

Write the balanced chemical equation.

Draw Lewis structures for each structure.

Explanation:

The balanced chemical equation for the combustion of methane is shown below:

[tex]2CH_3OH(g)+3O_2(g)->2CO_2(g)+ 4 H_2O(g)[/tex]

Lewis structures of the given molecules are shown below:

Answer:

E°(Ag⁺/Fe°) = 0.836 volt

Explanation:

3Ag⁺ + 3e⁻ => Ag°;            E° = +0.800 volt

Fe° => Fe⁺³ + 3e⁻ ;             E° = -0.036 volt

_________________________________

Fe°(s) + 3Ag⁺(aq) => Fe⁺³(aq) + 3Ag°(s) ...    

E°(Ag⁺/Fe°) = E°(Ag⁺) - E°(Fe°) = 0.800v - ( -0.036v) = 0.836 volt

Answer: the molecular formula of  trioxide is ClOClO3 or Cl2O4

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Answer:

oxidizer

Explanation:

an example of an oxidizers are oxygen and hydrogen peroxide