Can someone please please help

Answer:

An electrical conductivity meter (EC meter) measures the electrical conductivity in a solution. It has multiple applications in research and engineering, with common usage in hydroponics, aquaculture, aquaponics, and freshwater systems to monitor the amount of nutrients, salts or impurities in the water.

A general exponential expression is something like:

A^n

This means that we need to multiply the number A by itself n times.

Using that we will get (-2)^6 = 64

With that definition, we can rewrite:

(-2)^6 = (-2)*(-2)*(-2)*(-2)*(-2)*(-2)

So we just need to solve the above expression.

Also, remember the rule of signs:

(-)*(-) = (+)

We will get:

(-2)*(-2)*(-2)*(-2)*(-2)*(-2) =  [(-2)*(-2)]*[(-2)*(-2)]*[(-2)*(-2)]

                                        =  4*4*4 = 16*4 = 64

Then we got:

(-2)^6 = 64

If you want to learn more, you can read:

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The reaction between boric acid and sodium hydroxide is an example of a weak acid strong base reaction.

Boric acid is a weak acid while sodium hydroxide is a strong base.

Having that in mind, we know that a weak acid dissociates only to a small extent in solution while a strong base is almost 100% ionized in solution.

It the follows that a lot of OH- will be left behind after the reaction since only a little fraction of it reacts with the H^+ from boric acid.

Hence, if equal moles of boric acid (H3BO3) and NaOH fully react, OH- is left in the solution after reaction.

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Answer:

can only be determined experimentally.

Explanation:

In the early days of inorganic chemistry, the structure of complex ions remained a mystery hence the name ''complex''.

These ions appear to have structures that defied accurate elucidation. However, by diligent laboratory investigation, Alfred Werner was able to accurately determine the structure of cobalt complexes. As a result of this, he is regarded as a pathfinder in coordination chemistry.

Hence, the structure of complex ions can only be determined experimentally.

Answer:

c. can only be determined experimentally

Explanation:

It is not possible to know for certain the structure of a complex ion on the basis of stoichiometry or by the electrical charges on the components. The structure of the resulting complex ion can only be known by experiment.

Answer: Promotion of electrons is accompanied by a release of energy because of absorption of photon.

Explanation:

Promotion of electrons occurs when an electron accepts or absorbs a photon which leads to it's movement from a lower energy level orbital to a higher energy orbital.

According to Bohr, the electrons was restricted to certain energy levels and was thought to move along certain circular orbits around the nucleus. These energy levels were identified by means of principal quantum number, n. The wave mechanics model of atom does not restrict the electrons to a certain energy levels only. Instead it describes a region around the Nucleus called orbitals where there is a possibility of finding an electron with a certain amount of ENERGY.

The energy levels are composed of one or more orbitals and the distribution of electrons around the nucleus is determined by the number and kind of energy levels that are occupied.

Bohr made an assumption that an electron emits energy in the form of radiation when it moves from a higher to a lower permitted orbit, this produces a line in the atomic emission spectrum. Since the energies of the higher and lower orbits are fixed, the line will be of a particular energy and frequency.

do you have the specific heat for part 2?

Answer:

C. Golden rice enriched with vitamin A

Answer:

Remove 1 electron

Explanation:

In the atom of each element, there are three subatomic particles viz: proton, neutron and electron. The number of proton (positively charged) and electron (negatively charged) determines the charge of that element. The more the proton, the more positively charged an ion is and vice versa for electron.

According to this question, a neutral atom of lithium (Li) with atomic no. 3 is given i.e. a lithium atom with charge 0. To make the lithium atom's charge change to +1, ONE ELECTRON MUST BE REMOVED OR LOST.

Note that, the proton number (atomic number) of an element does not change, rather the electron number changes in relation to the no. of protons.

Answer:

it's level goes down

Explanation:

because the temperature is low, so mercury level is down

Answer:

Robert Millikan was a physicist who discovered the elementary charge of an electron using the oil-drop experiment

Answer:

the mass of an electron using the Oil-Drop experiment.

Explanation:

Answer:

6CO2+6H2O+heat" C6H12O6+6O2

the best way to balance a chemical reaction is to start with balancing the hydrogen followed by the other elements then lastly oxygen.so in this case if you put a 6 in front of carbon dioxide,water and oxygen you will definitely balance it.cause at the first side you have 6 carbons similar to the product,12 oxygen similar to the product and 18 oxygen similar to the products.

I hope this helps

Answer:

Explanation:

I saw this after answering your other question on the same reaction.

To balance the chemical reaction, look at the reactants and products. As O is part of both products, focus on C and H instead.

On the products side, 1 C6H12O6 has 6 C and 12 H. So that requires the same numbers of C and H on the reactant side because of mass conservation.

That gives 6 CO2 and 6 H2O as the reactants. Counting the number of O in the reactants, there are 6*2 + 6 = 18 O. Subtracting the 6 O in C6H12O6, that leaves 12 O so there are 12/2 = 6 O2 in the products.

Combining the numbers above, the balanced equation is:

___6___ CO₂ + ___6___ H₂O + heat ↔ ___1___ C₆H₁₂O₆ + ___6___ O₂

Answer:

I hope this helps!

Explanation:

The biggest threat caused by GM foods is that they can have harmful effects on the human body. It is believed that consumption of these genetically engineered foods can cause the development of diseases which are immune to antibiotics. ... As the health effects are unknown, many people prefer to stay away from these foods.

Answer:

C. water acts as a radiation shield to reduce the radiation level

Answer:

d) II and IV only.

Explanation:

A catalyst increases the kinetic energy of reactant molecules which increases the magnitude of collision. These then decreases the activation energy . A catalyst is not consumed by reaction because it is neither reactant nor a product, hence has no effect on equilibrium constant.

[tex].[/tex]

Answer:

A

Explanation:

it speed up a chemical reaction without being consumed by the reaction and increases the reaction rate by lowering the activation energy for a reaction but the average kinetic energy of the molecules remains the same well the required energy decreases

Answer:

It is a combustion reaction.

Answer:

The 3rd answer down.

Na²O (sodium oxide) will be a base when exposed to water H²O

Explanation:

Sodium Oxide Na²O, will become Sodium Hydroxide after being exposed to water (at 80% I believe).

The oxygen ion in Na²O has 2 extra electrons which makes it highly charged and very attractive to hydrogen ions. The attraction is so strong that when Na²O comes in contact with H²O, the O(-2) strips off a hydrogen from water, forming 2 x OH ions which of course are still strongly basic.

Answer:

D. [CO₂]

Explanation:

Let's consider the following equation at equilibrium.

CaCO₃(s) ⇄ CaO(s) + CO₂(g)

The equilibrium constant, Kc, is the ratio of the equilibrium concentrations of products over the equilibrium concentrations of reactants each raised to the power of their stoichiometric coefficients. It only includes gases and aqueous species.

Kc = [CO₂]

Answer:

all cells are produced from other preexisting cells through cell division

Finding Nemo??? sorry I really need these points

Answer:

2-nonyne

explanation:

First consider the type of bonds, there are tripple bonds of carbon to carbon, in position 2 from the right.

hence it us alkyn.

There are 9 carbons.

A) the enthalpy of fusion

Explanation:

the heat of vaporization, is the amount of energy needed to change a liquid to a gas at constant temperature and pressure. The energy required to melt a solid to a liquid is called the heat of fusion,  and the heat of sublimation is the energy.

Answer:

A

Explanation:

Edit : OPTION C is the answer

Option B is the best, Even though the cost is 30 Billion it essentially takes Lesser time to construct. For Plan A, They would have to construct the overground railway and then take a lot of time and effort to create wildlife corridors and then plant trees. Plan B takes much less time compared to plan A and might as well have a lesser impact on the environment!

The half life of a radioactive isotope refers to the time taken for half of the number of original number of atoms present in the sample to decay.

The equation below gives the number of atoms present at time t

[tex]N=Noe^-kt[/tex]

N = Number of atoms present at time t

No = Number of atoms initially present

k = decay constant

t = time taken

Given that;

t1/2 = 0.693/k

where t1/2 = half life

k = 0.693/t1/2

k = 0.693/ 55.6 s

k = 0.0125 s-1

Substituting values;

N = 16,000 e^-0.0125(0)

N = 16,000 atoms

At 50 s

N = 16,000 e^-0.0125(50)

= 8564 atoms

At 100 s

N = 16,000 e^-0.0125(100)

= 4584 atoms

At 200 s

N = 16,000 e^-0.0125(200)

= 1313 atoms

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Answer: 24 kcal

Explanation:

Given

Mass of water [tex]m=0.3\ kg[/tex]

Temperature of water [tex]T_1=0^{\circ}[/tex]

Heat of fusion [tex]L_f=80\ cal/g[/tex]

Heat of vaporization [tex]L_v=540\ cal/g[/tex]

Specific heat of water [tex]c=1\ cal/g.^{\circ}C[/tex]

Heat require to melt the ice is

[tex]\Rightarrow Q=mL_f\\\Rightarrow Q=0.3\times 1000\times 80\\\Rightarrow Q=24000\ cal\ or\ 24\ kcal[/tex]

Thus, 24 kcal of heat is required to melt 0.3 kg of ice.

Answer:

D. Propanol

Explanation:

C3H7OH the presence of alcohol functional group makes it propanol

Answer:

1. more

2. less

3. more

4. less

Explanation:

Answer:

0.034 M

Explanation:

1/[A] = kt + 1/[A]o

[A] = ?

k= 0.04556

t= 10.0 minutes or 600 seconds

[A]o = 0.50 M

1/[A] = (0.04556 × 600) + 1/0.50

[A] = 0.034 M

Answer:

Both substances undergo substitution reactions.

Explanation:

Let us go back to the idea of aromaticity. Aromatic substances are said to possess (4n + 2) π electrons according to Huckel rule.

Aromatic substances are unusually stable and the aromatic ring can not be destroyed by addition reactions.

Since both benzene and cyclooctatetraene are both aromatic, they do not undergo addition reactions whereby the aromatic ring is destroyed. They both undergo substitution reaction in which the aromatic ring is maintained.

Explanation:

chemical formula tells you the specific elements included in the compound and the number of atoms of each. The letters in a chemical formula are the symbols for the specific elements. So for example, H means hydrogen.

Explanation:

A chemical formula is a way of presenting information about the chemical properties of atoms that contribute a particular chemical compound or molecule, using chemical elements.