Match each phylum with the correct description
cnidarians
internal skeletons made of hardened plates
echinoderms
radial symmetry and stinging cells
arthropods
jointed body parts and an external skeleton
annelids
segmented body and closed circulatory
system

Answer:

1mole of gas at STP = 22.4dm3

0.0075 mole of CaCO3 = xdm3

cross multiply;

where 22.4dm3 = 22400cm3

x * 1 = 0.0075 * 22400 → 168cm3

the gas CO2 which evolved was gotten from CaCO3 so we use the number of moles of CaCO3 only

a) 1 - Trigonal planar 2 - Trigonal planar

b) 1- Linear  2 - Tetrahedral  3 - Tetrahedral

c) 1 - Trigonal planar 2 - Tetrahedral

We have to know that the shapes at the various carbon atoms and other atoms would depend on the number of the electron pairs and the hybridization of the atom.

We must have to note that the shape of the atom can be found on the basis of the valence shell electron pair repulsion theory which deals with the arrangement of that electrons around the outermost shell of the central atom.

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The most common example is the molar volume of a gas at standard temperature and pressure (STP), which is equal to 22.4 L for 1 mole of any ideal gas at 273.15 K and 1 atm of pressure.

Stoichiometry refers to the quantitative relationship between reactants and products. Calculating the quantities of reactants needed to make a given quantity of products, or the quantities of products resulting from a given quantity of reactants, is required in stoichiometric problems. Gas laws must be taken into account for the calculation if one or more reactants or products in a chemical reaction are gases. The findings of ideal gas law applications are often accurate to within 5%. We go over a few key ideas that are crucial for solving Stoichiometry Problems involving Gases in the sections below.

Stoichiometry and gas laws both rely on the mole notion as their foundation. A mole is an exact measurement of a substance. Based on the quantity of identities, a mole is a unit (i.e. atoms, molecules, ions, or particles). The number of identities in a mole of anything is equal to the number of atoms in exactly 12 grams of carbon-12, the most common isotope of carbon.

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Answer:

25

Explanation:

Isotopes of an element are the same element with different mass numbers but the same atomic number or the number of protons.

we know that in a balanced atom

Number of electrons = Number of protons = Atomic number

Atomic number (z) of manganese = 25

For Mn+5, the number of protons remains the same = 25

However, the number of electrons on Mn+5 = 21

Answer: 25

Explanation:

The variables that might affect the investigation while dissolving different masses of salt are temperature and mass of the salt.

A variable that changed during the inquiry is regarded as an independent variable and is called "mass of salt dissolved in water." While the investigation's dependent variable, "boiling point of salt solution," is a variable that was monitored.

There are numerous things that can be changed to see how they affect other things. Variables are the changeable quantities. Any element, character trait, or condition that can exist in a variety of forms or concentrations is a variable. Independent, dependent, and controlled variables are the three types of variables that often make up an experiment.

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Neera and Tom dissolved different masses of salt in 500 cm3 of water.

They measured the temperature at which each salt solution boiled.

(a) They wrote down the variables that might affect the investigation.

(i) What is the independent variable (the variable they changed) in

their investigation?

(ii) What is the dependent variable (the variable they measured) in

their investigation?

(iii) Which variable above would affect the experiment the least?

Answer:

COVALENT

Explanation:

covalent and is formed by the sharing of two valence electrons.

Answer:

Force B

Explanation:

Gravity pulls "down"  :D

Hoped this helped!

Have a nice day!

Explanation:

In natural radioactive decay, three common emissions occur. When these emissions were originally observed, scientists were unable to identify them as some already known particles and so named them:

alpha particles ( α )

beta particles (β)

gamma rays (γ)

These particles were named using the first three letters of the Greek alphabet. Some later time, alpha particles were identified as helium-4 nuclei, beta particles were identified as electrons, and gamma rays as a form of electromagnetic radiation like x-rays, except much higher in energy and even more dangerous to living systems.

The functional group of molecules as follows :

Molecule 1. is aldehyde and ketone, Molecule 2 is acid and thio, Molecule 3 is acid and amide, Molecule 4 is alcohol and ether, Molecule 5 is Alcohol and acid. The image attached below show the functional group and molecules are labeled.

The polar compounds are those compound having different positive and negative charge, therefore the bonding with atoms such as nitrogen, oxygen, or sulfur.

A buffer is a solution the can control the pH change along with the addition of an acidic or basic substance. It is able to neutralize small amounts of added acid or base, So it maintains the pH of the solution. This is important to maintain pH ranges.

Thus, Molecule 1. is aldehyde and ketone, Molecule 2 is acid and thio, Molecule 3 is acid and amide, Molecule 4 is alcohol and ether, Molecule 5 is Alcohol and acid.

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Answer: An electron con only exist in a limited number of quantized energy levels.

Explanation:

1) T

2) F

3) F

4) F

5) T

6) F

7) T

8) T

9) F

10) ...T... grams are usually in lowercase g

Answer:

23.12 atm

Explanation:

First, add together the moles of the two samples:

5.25 moles + 4.20 moles = 9.45 moles

273 + 25 = 298 K for the temperature

volume is 10.0 L

Since we have moles now, we have to rearrange our ideal law equation to solve for pressure:

[tex]P = \frac{nRT}{V}[/tex]

[tex]\frac{(9.45 moles) X (0.08206) X (298 K)}{10.0 L}[/tex]

9.45 X .08206 X 298 all divided by 10.0 = 23.09202 atm (or 23.12)

Answer:

T₂ = 128.19 K

Explanation:

Given that,

The initial volume, V₁ = 12.5 ft³

Initial temperature, T₁ = -173 °C = 100.15 K

Final volume, V₂ = 16 ft³

We need to find the new temperature. The relation between temperature and volume is given by :

[tex]V\propto T\\\\\dfrac{V_1}{V_2}=\dfrac{T_1}{T_2}[/tex]

Put all the values,

[tex]T_2=\dfrac{T_1V_2}{V_1}\\\\T_2=\dfrac{100.15\times 16}{12.5}\\\\T_2=128.19\ K[/tex]

So, the new temperature is 128.19 K.

Answer:

23 atm

Explanation:

Step 1: Given data

Step 2: Calculate the final pressure of the gas

If we assume constant temperature and ideal behavior, we can calculate the final pressure of the gas using Boyle's law.

P₁ × V₁ = P₂ × V₂

P₂ = P₁ × V₁ / V₂

P₂ = 90 atm × 2.5 L / 10 L = 23 atm

As expected, since the volume increased, the pressure decreased.

Answer:

Wash hands and surfaces often. Harmful bacteria can spread throughout the kitchen and get onto cutting boards, utensils, and counter tops. To prevent this: Wash hands with soap and hot water before and after handling food, and after using the bathroom, changing diapers; or handling pets.

Answer:

Explanation:

V1*P1= V2*P2

6.8L*0.91atm=1.0atm*x

x=6.188 L

Answer:31.7ml

Explanation:

Answer: The correct answer is in an exothermic reaction the energy of the product is less than the energy of the reactants.

Explanation: got it

The energy of reactants is not equal to that of products as the reaction is an exothermic reaction.

An exothermic reaction is defined as a chemical reaction which involves release of energy in the form of light,heat .In these reactions, energy is transferred from system to surroundings rather than taking energy from surroundings into system as in endothermic reactions.

In an exothermic reaction,change in enthalpy is negative.Therefore, it can be inferred that net amount of energy which is required to start the exothermic reaction is less than the net amount which is released by the reaction.

Examples of exothermic reactions are combustion reactions, detonation of nitroglycerin , neutralization reactions and nuclear fission.

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Answer:

See whole explanation to understand

Explanation:

the reason why there is such a large jump from 2nd to 3rd ionization energy for calcium is because to remove the third electron, a larger amount of energy is required, since the shell is closer to the nucleus, and higher attraction exists between them. This is why the second ionization energy is 1125.4 and then the third IE is 4912.4 which is a very big difference. It's all about the elections and energy!!

Atoms of different element can not have same atomic number because only same type of atoms combine to form element. Atoms belonging to different element can have different atomic number. Therefore, higher attraction between shell and nucleus, there is such a large jump from 2nd to 3rd ionization energy.

Element generally consist of atoms or we can atoms combine to form element. Atoms of an element is always same, means all the properties of all atoms of one type of element is same. Two or more than two atoms with different physical or chemical properties can not combine together to form an element.

The reason why there is such a large jump from 2nd to 3rd ionization energy for calcium is because to remove the third electron, a larger amount of energy is needed, since the shell is closer to the nucleus, and higher attraction exists between them.

Therefore, higher attraction between shell and nucleus, there is such a large jump from 2nd to 3rd ionization energy.

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Answer:

C. Release CO2 due to can opening

Explanation:

Le Châtelier’s principle states that when a reaction is at equillibrium and it is disturbed it will respond to return to equilibrium.

SO

H2O(l) + CO2(g) <-------------------> H2CO3(aq)

When you open a bottle of coke it is under pressure and not at equillibrium so it reacts by releasing the gas to reach equilibrium it can be seen in the equation above just that this is for club soda not coke, the idea applies though

The definition of a transition metal is that it must have an incompleted sub-level in one or more of its oxidation states. As zinc has a completed sub-level at all oxidative states, so it can't be considered a transition metal.

Answer:

The correct answer is - a physical change because the material remains the same.

Explanation:

A chemical change is the change that results in the formation of the new element or the substance whereas the physical change remains the same material or substance even after the change.

The physical change can be a change in density, size, shape, or volume, and other properties. In the recycling of the aluminum can the material remain the same only shape or size of the aluminum change order to reuse.

Answer:

its D i promise

Explanation:

Solution :

a). Applying the energy balance,

[tex]$\Delta E_{sys}=E_{in}-E_{out}$[/tex]

[tex]$0=\Delta U$[/tex]

[tex]$0=(\Delta U)_{iron} + (\Delta U)_{water}$[/tex]

[tex]$0=[mc(T_f-T_i)_{iron}] + [mc(T_f-T_i)_{water}]$[/tex]

[tex]$0 = 27 \times 0.45 \times (T_f - 375) + 130 \times 4.18 \times (T_f-26)$[/tex]

[tex]$t_f=33.63^\circ C$[/tex]

b). The entropy change of iron.

[tex]$\Delta s_{iron} = mc \ln\left(\frac{T_f}{T_i} \right)$[/tex]

           [tex]$ = 27 \times 0.45\ \ln\left(\frac{33.63 + 273}{375 + 273} \right)$[/tex]

           = -9.09 kJ-K

Entropy change of water :

[tex]$\Delta s_{water} = mc \ \ln\left(\frac{T_f}{T_i} \right)$[/tex]

           [tex]$ = 130 \times 4.18\ \ln\left(\frac{33.63 + 273}{26 + 273} \right)$[/tex]

           = 10.76 kJ-K

So, the total entropy change during the process is :

[tex]$\Delta s_{tot} = \Delta s_{iron} + \Delta s_{water} $[/tex]

        = -9.09 + 10.76

         = 1.67 kJ-K

c). Exergy of the combined system at initial state,

[tex]$X=(U-U_{0}) - T_0(S-S_0)+P_0(V-V_0)$[/tex]

[tex]$X=mc (T-T_0) - T_0 \ mc \ \ln \left(\frac{T}{T_0} \right)+0$[/tex]

[tex]$X=mc\left((T-T_0)-T_0 \ ln \left(\frac{T}{T_0} \right)\right)$[/tex]

[tex]$X_{iron, i} = 27 \times 0.45\left(((375+273)-(12+273))-(12+273) \ln \frac{375+273}{12+273}\right)$[/tex]

[tex]$X_{iron, i} =63.94 \ kJ$[/tex]

[tex]$X_{water, i} = 130 \times 4.18\left(((26+273)-(12+273))-(12+273) \ln \frac{26+273}{12+273}\right)$[/tex]

[tex]$X_{water, i} =-13.22 \ kJ$[/tex]

Therefore, energy of the combined system at the initial state is

[tex]$X_{initial}=X_{iron,i} +X_{water, i}$[/tex]

            = 63.94 -13.22

            = 50.72 kJ

Similarly, Exergy of the combined system at initial state,

[tex]$X=(U_f-U_{0}) - T_0(S_f-S_0)+P_0(V_f-V_0)$[/tex]

[tex]$X=mc\left((T_f-T_0)-T_0 \ ln \left(\frac{T_f}{T_0} \right)\right)$[/tex]

[tex]$X_{iron, f} = 27 \times 0.45\left(((33.63+273)-(12+273))-(12+273) \ln \frac{33.63+273}{12+273}\right)$[/tex]

[tex]$X_{iron, f} = 216.39 \ kJ$[/tex]

[tex]$X_{water, f} = 130 \times 4.18\left(((33.63+273)-(12+273))-(12+273) \ln \frac{33.63+273}{12+273}\right)$[/tex]

[tex]$X_{water, f} =-9677.95\ kJ$[/tex]

Thus, energy or the combined system at the final state is :

[tex]$X_{final}=X_{iron,f} +X_{water, f$[/tex]

            = 216.39 - 9677.95

            = -9461.56 kJ

d). The wasted work

[tex]$X_{in} - X_{out}-X_{destroyed} = \Delta X_{sys}$[/tex]

[tex]$0-X_{destroyed} = $[/tex]

[tex]$X_{destroyed} = X_{initial} - X_{final}$[/tex]

                = 50.72 + 9461.56

                = 9512.22 kJ

Answer:

the answer is the last one , sorry if im wrong.

Explanation: