Assignment
Explain why it is not advisable to wear
black silky cloth in the sun​

Answer:

the answers are in the pic

Explanation:

Answer:

12.36, 52.49, 40.13

Explanation:

Step 5 for the copper one

Answer: 1 A for each lamps

Explanation: we assume lamps are similar and lamps have same resistance.

Then current is divided according Kirchhoff s law equally to all lamps.

Answer:

(i) Concentrated HNO3 can be stored and transported in aluminium containers as it reacts with aluminium to form a thin protective oxide layer on the aluminium surface. This oxide layer renders aluminium passive. (ii) Sodium hydroxide and aluminium react to form sodium tetrahydroxoaluminate(III) and hydrogen gas.

Answer:

[tex]\boxed {\boxed {\sf 5.2 *10^{22} \ molecules \ NaCl}}[/tex]

Explanation:

1. Convert grams to moles

First, convert grams to moles using the molar mass. This can be found on the Periodic Table.

Sodium (Na) has an oxidation state of +1 and chlorine (Cl) has an oxidation state of -1, so they combine in a 1:1 ratio for a formula of NaCl. We can simply add their moles masses.

Use this as a ratio.

[tex]\frac {58.4397693 \ g \ NaCl}{ 1 \ mol \ NaCl}[/tex]

Multiply by the given number of grams.

[tex]5.0 \ g \ NaCl *\frac {58.4397693 \ g \ NaCl}{ 1 \ mol \ NaCl}[/tex]

Flip the fraction so the grams of sodium chloride cancel.

[tex]5.0 \ g \ NaCl *\frac {1 \ mol \ NaCl}{ 58.4397693 \ g \ NaCl}[/tex]

[tex]5.0 *\frac {1 \ mol \ NaCl}{ 58.4397693 }=\frac {5.0 \ mol \ NaCl} { 58.4397693 } = 0.0855581749 \ mol \ NaCl[/tex]

2. Convert moles to molecules

We must use Avogadro's Number. This tells us the amount of particles (molecules, atoms, etc.) in 1 mole of a substance. In this case, it is molecules of sodium chloride.

[tex]\frac{6.022*10^{23} \ molecules \ NaCl} {1 \ mol \ NaCl}[/tex]

Multiply by the number of moles we calculated.

[tex]0.0855581749 \ mol \ NaCl*\frac{6.022*10^{23} \ molecules \ NaCl} {1 \ mol \ NaCl}[/tex]

The moles of sodium chloride cancel.

[tex]0.0855581749 *\frac{6.022*10^{23} \ molecules \ NaCl}{1}=5.15231329*10^{22} \ molecules \ NaCl[/tex]

The original measurement of grams has 2 (2 and 0) significant figures, so our answer must have the same. For the number we calculated, that is the hundredth place. The 5 in the hundredth place tells us to round the 1 to a 2.

[tex]5.2 *10^{22} \ molecules \ NaCl[/tex]

Answer:

pH = 11.216.

Explanation:

Hello there!

In this case, according to the ionization of ammonia in aqueous solution:

[tex]NH_3+H_2O\rightleftharpoons NH_4^++OH^-[/tex]

We can set up its equilibrium expression in terms of x as the reaction extent equal to the concentration of each product at equilibrium:

[tex]Kb=\frac{[NH_4^+][OH^-]}{[NH_3]} \\\\1.80x10^{-5}=\frac{x*x}{0.150-x}[/tex]

However, since Kb<<<1 we can neglect the x on bottom and easily compute it via:

[tex]1.80x10^{-5}=\frac{x*x}{0.150}\\\\x=\sqrt{1.80x10^{-5}*0.150}=1.643x10^{-3}M[/tex]

Which is also:

[tex][OH^-]=1.643x10^{-3}M[/tex]

Thereafter we can compute the pOH first:

[tex]pOH=-log(1.643x10^{-3}M)\\\\pOH=2.784[/tex]

Finally, the pH turns out:

[tex]pH=14-2.784\\\\pH=11.216[/tex]

Regards!

Answer:

Shared (bonding) electrons : 8

Unshared (lone, non-bonding) electrons : 16

Explanation:

The Lewis dot stricture of the molecule attached to this answer shows us all the valence electrons present in the molecule.

Altogether, we have a total number of 24 valence electrons in SO3.

There are eight electrons shared between atoms of elements, these are the bonding electrons.

There are sixteen electrons that are not shared between atoms of elements, These are the lone or non-bonding electrons.

Hence, there are four shared pairs of electrons and eight pairs of unshared electrons.

Explanation:

X = Group 1 metal

Y = Group 7 Non metal

The dots basically signifies the group.

Metal loses electrons and non metal gains electron. The valency of X is 1 and that of Y is 7.

X atom loses one electron and Y atom gains one electron.

The bond that forms between a metal and a non metal is an ionic bond.

Answer:

3.62

Explanation:

Using the Henderson-Hasselbach equation:

pH = pKa + log[base]/[acid]

pH = -log(1.8 x 10^-4) + log(0.15/0.20) = 3.62

The pH of acid is between 0-7 on pH scale while for base pH range is from 7-14. Therefore, the pH of of the buffer solution comprised of 0.20 M HCHO₂ and 0.15 M NaCHO₂. (Ka for HCHO2 = 1.8 x 10⁻⁴) is 3.62. pH is a unitless quantity.

pH is a measurement of amount of hydronium ion H₃O⁺ in a given sample. More the value of hydronium ion concentration, more will be the solution acidic.

On subtracting pH from 14, we get pOH which measures the concentration of hydroxide ion in a given solution. pH depend on the temperature. At room temperature pH scale is between 0 to 14. pH of neutral solution is 7.

Using the Henderson-Hassel Bach equation:

pH = pKa + log[base]/[acid]

pH = -log(1.8 x 10^-4) + log(0.15/0.20) = 3.62

Therefore, the pH of of the buffer solution comprised of 0.20 M HCHO2 and 0.15 M NaCHO2. (Ka for HCHO2 = 1.8 x 10-4) is 3.62.

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Answer:

uhhh not really i don't even know what that is LOL

Answer:

metal

Explanation:

it's a soft silvery metal

oxygen  is needed as a reactant for cellular respiration

Cellular respiration can be defined as the process  which occurs in every cells mainly mitochondria of plants and animals, it involve in the break down of sugars in the presence of oxygen and releases energy in the form of ATP.

The waste product of this process are carbon dioxide and water during exhalation process done  by lungs,  breathing and cellular respiration are related to each other.

At every step of cellular respiration energy is used in the form of ATP and carry out the normal function. It can aerobic and anaerobic respiration on the basis of use of oxygen.

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Answer:

Pb(NO₃)₂ is the limiting reactant.

The equation is: Pb(NO₃)₂ (aq) + 2KCl (aq) →  PbCl₂ (s) ↓  + 2KNO₃ (aq)

Explanation:

We identify our reactants:

Pb(NO₃)₂ → Lead (II) nitrate

KCl → Potassium chloride

Our reaction is:

Pb(NO₃)₂ (aq)  +  2KCl (aq) →  PbCl₂ (s) ↓  + 2KNO₃ (aq)

1 mol of Lead (II) nitrate reacts to 2 moles of KCl, in order to produce 2 moles of potassium nitrate and 1 mol of slid Lead (II) chloride.

We determine the moles of the reactants:

6.06 g . 1mol /331.2 g = 0.0183 moles of Lead (II) nitrate

6.58 g . 1mol / 74.55g = 0.0882 moles of KCl

2 moles of KCl react to 1 mol of Pb(NO₃)₂

Then, 0.0882 moles of KCl may react to (0.0882 . 1) /2 = 0.0441 moles

We have 0.0183 moles of Pb(NO₃)₂ and we need 0.441 moles. Then, the

Pb(NO₃)₂ is our limiting reactant.

C. picking a tray in the cafeteria line

Answer:

I think it would double it's self

The electrons, in redox reaction get partially transferred by one to another element.

A redox reaction occurs when the oxidation states of the substrate change. The loss of electrons or maybe an increase in the oxidation state of a chemical and its atoms is referred to as oxidation. The gain of electrons or a reduction in the oxidation state of either a chemical or its atoms is referred to as reduction. The oxidation as well as reduction process can be seen in same reaction which is introduced as redox reaction.

Electron can be considered as sub atomic particle which carry negative charge on it.

The given reactions are:

a. Ca(s) + Cl2(g) → CaCl2(s)

b. 4Cu(s) + O2(g) → 2Cu2O(s)

After transferring two electron in both reaction Ca and Cu it will form  CaCl2 and 2Cu2O.

Therefore, after transferring partially electrons one elements get converted into another kind of molecule

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Answer:

potential energy

Explanation:

Explanation:

I don't really understand the question

Answer:

Combining the two clear colorless liquids is a chemical change because a different solid substance is formed. Tell students that a precipitate is an insoluble solid that forms when two solutions are combined and react chemically. Insoluble means that the solid will not dissolve.

Explanation:

Answer:

Explanation:

Mass = 66.6 gram

Density = 0.790 g/mL

Volume = Mass ÷ Density

Volume = 66.6 ÷ 0.790

Volume = 84.30 mL

Answer:

CH4

Explanation:

Tetra is the prefix for four. Hence the H4

Mono is the prefix for one, Hence the C

Methane (aka Tetrahydrogen monocarbide) written as CH4

Answer:

Close packing in crystals refers to space efficient arrangement of constituent particles in a crystal lattice. To understand this packing more clearly we have to assume all particles (atoms, molecules and ions) are of the same spherical solid shape. So the unit cell of a lattice is a cubic shape.

Explanation:

Hope it helps! Correct me if I am wrong :>

Im sure about my answer :>

If you dont mind can you please mark me as brainlest?

Answer:

I think 4 I'm not completely sure

Explanation:

I hope it's right

hope it helps you ❣❣

Mark me as brainliest

Answer:

It’s 10

Explanation:

I looked it up

To solve this we must be knowing each and every concept related to  energy and its calculations. Therefore,  at point b, 10joule of energy is present.

Energy is defined in physics as the ability to accomplish work or heat items. It's a scalar measurement with magnitude but no direction. Energy is maintained, which implies it can change forms but is not generated or destroyed. potential energy transforms into kinetic energy.

One type of energy can be transferred into another without breaking a thermodynamic rule. Not all of these energy sources are equally beneficial in practical applications. At point a the object has 30 joules of energy. At point b, 10joule of energy is present.

Therefore,  at point b, 10joule of energy is present.

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Answer:

Mouthing is the answer to your question

Answer:

Yes, they work in space. I forgot an example, will edit the post when I found it

Hope this helps!

Answer:

To calculate the concentration of the acid solution, use three steps.

1. Use the volume of base used at the endpoint and the known concentration of the base solution to find the moles of base used.

2. Use the stoichiometry to find the moles of acid from the moles of base.

3. Divide the moles of acid by the volume of acid used in the titration to find the concentration of acid.

Explanation:

Titration is the process used in volumetric analysis to determine the amount of a substance present in a given sample.

In any titration, a solution of known concentration known as the standard solution is used to react with a solution of of unknown concentration. The reacting volumes of the solutions are then used to calculate the unknown  concentration of the second solution.

In acid-base neutralization reactions, an equivalence point/endpoint of the neutralization titration is obtained and is the point at which the moles of H+ is equal to the moles of OH- . An indicator is used to indicate the equivalence point during a titration by a color change observed in the indicator.

In order to calculate the concentration of an acid, we need to know accurately, use three steps:

1. Use the volume of base used at the endpoint and the known concentration of the base solution to find the moles of base used.

2. Use the stoichiometry of the reaction to find the moles of acid from the moles of base.

3. Divide the moles of acid by the volume of acid used in the titration to find the concentration of acid.

In order to calculate the concentration of a base, use three steps:

1. Use the volume of acid used at the endpoint and the known concentration of the acid solution to find the moles of acids used.

2. Use the stoichiometry of the reaction to find the moles of base from the moles of acid.

3. Divide the moles of base by the volume of base used in the titration to find the concentration of base.

Answer:

[tex][OH^-]=2.455x10^{-3}M[/tex]

Explanation:

Hello there!

In this case, since a strong base produce OH ions in solution, it possible to first compute the pOH as shown below:

[tex]pH+pOH=14\\\\pOH=14-pH\\\\pOH=14-11.39\\\\pOH=2.61[/tex]

Thus, via the definition of the pOH we can compute the concentration of the strong base as follows:

[tex]pOH=-log([OH^-])[/tex]

Thus, solving for the concentration we obtain:

[tex][OH^-]=10^{-pOH}=10^{-2.61}[/tex]

[tex][OH^-]=2.455x10^{-3}M[/tex]

Best regards!