4.1 shows a plant cell. g For Examiner's Use n. C D Fig. 4.1 (i) Name the type of plant cell shown in Fig. 4.1. [1]​

Answer:

Below!

Explanation:

Isotopes are elements with a similar chemical makeup and the same atomic number, but a different atomic mass and number of neutrons . An example of this would be carbon-12, carbon-13, and carbon-14. Three isotopes of the element carbon that have the same 6 protons but have a different neutron count. A simple way to explain isotopes would be to say that they are just different "versions" of an element.

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Answer:

in sodium sulphate there is sodium an sulphur

Answer:

7.2

Explanation:

you first have to find the number of moles of nitrogen dioxide by using the number of moles for calcium nitrate and the mole to mole ratios

number of moles of calcium nitrate=mass/mm

=16.4/102

=0.16g/mol

then you use the mole to mole ratios

2 : 4

0.16: x

2x/2=0.64/2

x=0.32g/moles of nitrogen dioxide

then you use the formula for the volume

v=22.4n

=22.4×0.32

=7.2

I hope this helps

is any musical instrument that creates sound primarily by the vibration of the instrument itself without the use of air flow

Answer:

Explanation:

A. Ethanoic acid-acetic acid being weak acid dissocated weekly and turns solution to weakly acidic, ph will be between 4-7,

B. Hydrochloric acid - the solution would be acidic- with lots of H+ ions, Ph will be between 1-4,

C. Sodium chloride - solution prodcued netural Na+ and Cl- hence wont affect ph of solution will be equalt to 7.

D. Sodium hydrogen carbonate-NaHCO3 is weak base and the PH will be above 7,

Answer:

C. Its viscosity decreases with increasing temperature

Explanation:

Answer:

okay so basically what you are being tested is if you know the difference between simple and fractional distillation and okay you can evaporate the mixture but you won't obtain water so you will use simple distillation to obtain both salt and water

Answer:

Explanation: since oxalic acid is a weak acid it wont provide a strong acidic medium. So in order to provide a strong acidic medium dilute sulphuric acid is added.

A. 0.038 g.

Explanation:

The decay of carbon-14 is a first order reaction.

The rate constant of the reaction (k) in a first order reaction = ln (2)/half-life = 0.693/(5730 year) = 1.21 x 10⁻⁴ year⁻¹.

The integration law of a first order reaction is:

kt = ln [Ao]/[A]

k is the rate constant = 1.21 x 10⁻⁴ year⁻¹.

t is the time = 17,190 years.

[Ao] is the initial concentration of carbon-14 = 0.300 g.

[A] is the remaining concentration of carbon-14 = ??? g.

∵ kt = ln [Ao]/[A]

∴ (1.21 x 10⁻⁴ year⁻¹)(17,190 years) = ln (0.300 g)/[A]

2.08 = ln (0.300 g)/[A]

Taking exponential for both sides:

8.0 = (0.300 g)/[A]

∴ [A] = 0.0375 g ≅ 0.038 g

Answer:

67.3g

Explanation:

%(w/w) = mass of solute/total mass of solution × 100

According to this question, an aqueous solution contains 32.7% KCl (w/w%). Firstly, we find the mass of the solute (KCl) as follows, if the mass of solution is 100g:

32.7 = mass of solute/100 × 100

mass of solute (KCl) = 32.7g

Mass of solution = mass of solvent (water) + mass of solute (KCl)

100g = x + 32.7g

x = 100 - 32.7

x = 67.3

Hence, the mass of water contained in the 100g solution is 67.3g.

Answer:

A. An indicator added to the solution turns green-blue.

Explanation:

A pH scale measures the concentration of hydrogen ions in acidic and alkaline solutions.

In chemistry, pH literally means the power of hydrogen ions and it is a measure of the molar concentration of hydrogen ions in a particular solution; thus, specifying the acidity, neutrality or basicity of any chemical solution.

Mathematically, the pH of a solution is given by the formula;

[tex] pH = -log_{10}(H^{+}) [/tex]

On a pH scale, a solution with a pH of 7 is neutral, a solution with a pH below 7 is acidic and it's basic (alkaline) when it's pH is above 7.

A pH indicator can be defined as a compound (substance) that indicates the concentration of hydrogen ions present in a solution by changing its color over a narrow range of pH values.

A pH range of 1 to 3 (1 - 3) represents a strong acid with a red color.

When an indicator added to a solution turns green-blue, it simply means that a weak base is present.

Answer: B is the correct answer

Explanation:

The energy of a photon is 4.44×[tex]10^{-19}[/tex]J for the wavelength of 448 nm.

So, option (B) is correct. This can be calculated by using the energy formula.

The energy of a photon is said to be photon energy. It is directly proportional to the photon's electromagnetic frequency and inversely proportional to the wavelength. If the frequency of the photon is high then its energy is also high.

The energy of a photon, E=hc/λ

Given that,

λ = 448nm

h= 6.63×[tex]10^{-34}[/tex]J/s

E = 6.63×[tex]10^{-34}[/tex]×3×[tex]10^8[/tex]/448×[tex]10^-^9[/tex]

E = 4.44×[tex]10^{-19}[/tex] J

Hence option (B) is correct.

Therefore, the energy of a photon emitted with a wavelength of 448nm is  4.44×[tex]10^{-19}[/tex] J.

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Answer:

c. ammonia window cleaner

Explanation:

Window cleaners contain ammonia (a base) for the purpose of removing the dust and grease on the windows.

digestive juices, orange(a citrus) juice, and vinegar are all highly acidic.

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Answer:

Electrolysis is commercially important as a stage in the separation of elements from naturally occurring sources such as ores using an electrolytic cell

Answer:

convection is my correct answer

Answer:

Nucleus is the answer

A micrograph of animal cells, showing the nucleus (stained dark red) of each cell. Known as the cell's “command center,” the nucleus is a large organelle that stores the cell's DNA (deoxyribonucleic 

Answer:

nucleus is the part of a cell directs the cells Activities and holds it's DNA

Answer:

D.[Ne] 3S2 3P2

Explanation:

The electron configuration for silicon is  [Ne] 3s² 3p². Hence Option (C) is correct.

Electronic configuration, also called electronic structure or electron configuration, the arrangement of electrons in orbitals around an atomic nucleus.

The electron configuration of an element describes how electrons are distributed in its atomic orbitals.

Electron configurations of atoms follow a standard notation in which all electron-containing atomic subshells (with the number of electrons they hold written in superscript) are placed in a sequence.

Silicon belongs to group 14th and 3rd period.Therefore, The electron configuration for silicon is  [Ne] 3s² 3p². Hence Option (C) is correct.

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Answe:

Explanation:

số mol của H2S là : 68/22.4=3.03 nha

Answer:

2Na + 2H2O → 2NaOH + H2

Explanation:

A balanced equation is an equation for a chemical reaction in which the number of atoms for each element in the reaction and the total charge are the same for both the reactants and the products.

Answer:

C6H12O6+6O2--->6CO2+6H2O

Explanation:

So I went through all the answers and could not find the right one amongst. If I'm not wrong the reaction above is the reaction for respiration. The nearest answer is D but unfortunately the first reactant isn't in accordance with that which the question has given.

Answer: Science : Chemistry, astronomy , biology , physics , biology ,geology. Notscience : Astrology and theology

Explanation: Astrology and theology are non scientific areas of study.

Answer:

sulphuric acid's formula is H²SO⁴

Explanation:

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The answer is 32 grams!

hope I helped

Answer:

a. The temperature should be increased.

b. 342.86K

Explanation:

Using Charles law equation as follows:

V1/T1 = V2/T2

Where;

V1 = initial volume (mL)

V2 = final volume (mL)

T1 = initial temperature (K)

T2 = final temperature (K)

According to this question, the following information were given:

V1 = 210mL

V2 = 360mL

T1 = -73°C (-73 + 273 = 200K)

T2 = ?

Using V1/T1 = V2/T2

210/200 = 360/T2

Cross multiply

200 × 360 = 210 × T2

72000 = 210T2

T2 = 72000/210

T2 (new temperature) = 342.86K

Answer:

The current of the toaster is 3.93A

Explanation:

Using the GRASS method:

G: Given: The information that is given is that we have 28Ω of Resistance and 110V of voltage.

R: Required: We need to find the current measured.

A: Action: We can use Ohm's law that relates resistance, voltage and current in the equation:

V = R*I

Or:

I = V/R

Where I is current in A, V is voltage = 110V and R is resistance = 28Ω

S: Solve:

I = 110V / 28Ω

I = 3.93A

S: Statement:

Answer:

D

Explanation:

according to boyle's law the temperature and pressure of a gas are inversely proportional given by the equation

p1v1=p2v2

In this case p1 is 9.5,v1 is 1.7,v2 is 1.1 and we have to find p2

9.5×1.7=p2×1.1

16.15/11=1.1p2/1.2

p2=14.7

I hope this helps

Answer:

[tex]\boxed {\boxed {\sf D.\ 14.7 \ atm}}[/tex]

Explanation:

We are asked to find the pressure on a gas given a change in volume. We will use Boyle's Law which states the volume of a gas is inversely proportional to the pressure. The formula for this law is:

[tex]P_1V_1=P_2V_2[/tex]

The gas originally has a pressure of 9.5 atmospheres and a volume of 1.7 liters.

[tex]9.5 \ atm * 1.7 \ L = P_2V_2[/tex]

The gas is compressed to a volume of 1.1 liters, but the pressure is unknown.

[tex]9.5 \ atm * 1.7 \ L = P_2* 1.1 \ L[/tex]

We want to find the new pressure, so we must isolate the variable P₂. It is being multiplied by 1.1 liters. The inverse operation of multiplication is division. Divide both sides of the equation by 1.1 L.

[tex]\frac {9.5 \ atm * 1.7 \ L}{1.1 \ L} =\frac{ P_2* 1.1 \ L}{1.1 \ L}[/tex]

[tex]\frac {9.5 \ atm * 1.7 \ L}{1.1 \ L} =P_2[/tex]

The units of liters cancel.

[tex]\frac {9.5 \ atm * 1.7 }{1.1 } =P_2[/tex]

[tex]\frac {16.15}{1.1} \ atm =P_2[/tex]

[tex]14.6818181818 \ atm= P_2[/tex]

Round to the tenths place. The 8 in the hundredth place tells us to round the 6 up to a 7.

[tex]14.7 \ atm \approx P_2[/tex]

The new pressure at a volume of 1.1 liters is approximately 14.7 atmospheres.

Answer:

Below!

Explanation:

Lithium (Li) is more reactive than Beryllium (Be). This is because Lithium lacks the valence electron that Beryllium has. Elements with a lower amount of valence electrons are less stable than those with full valence shells, causing it to react more easily. Because Lithium only contains 1 valence electron, it is easily transferred/given up to create bonds and form compounds.

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Compared to beryllium, lithium (Li) is much more reactive (Be). This is due to Lithium's lack of Beryllium's valence electron.

Reactivity in chemistry is a gauge of the ease with which a substance reacts chemically. The chemical may react independently or in combination with other atoms and compounds, and in either case, energy will typically be released. The most reactive substances and elements have the potential to spontaneously or explosively ignite.

They typically ignite when exposed to oxygen in the atmosphere and water. Reactivity is temperature-dependent. The available energy for just a chemical reaction increases with temperature, often increasing its likelihood. The noble gases are the least reactive elements. Hydrogen is the least active catalyst in this group and doesn't produce any stable compounds. Compared to beryllium, lithium (Li) is much more reactive (Be). This is due to Lithium's lack of Beryllium's valence electron.

Therefore, compared to beryllium, lithium (Li) is much more reactive (Be). This is due to Lithium's lack of Beryllium's valence electron.

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