Can someone help me please

The atomic symbol superscript 40 subscript 19 upper k. represents potassium-40 (k-40), a radioactive isotope that has 19 protons

Oksana_A [137]

Answer:

40/18AR

Explanation:

sorry my answer was late but i hope this helps someone else! I got it right on the test

8 0

2 years ago

Which component of a river system is made of streams and small rivers that feed into a large river? Which component of a river s

inn [45]

Explanation: A river drainage basin is an area drained by a river and all of its tributaries. A river basin is made up of many different watersheds. A watershed is a small version of a river basin. Every stream and tributary has its own watershed, which drains to a larger stream or wetland.

8 0

3 years ago

If 21.00 mL of a 0.68 M solution of C6H5NH2 required 6.60 mL of the strong acid to completely neutralize the solution, what was

Andru [333]

Answer:

pH = 2.46

Explanation:

Hello there!

In this case, since this neutralization reaction may be assumed to occur in a 1:1 mole ratio between the base and the strong acid, it is possible to write the following moles and volume-concentrations relationship for the equivalence point:

$n_{acid}=n_{base}=n_{salt}$

Whereas the moles of the salt are computed as shown below:

$n_{salt}=0.021L*0.68mol/L=0.01428mol$

So we can divide those moles by the total volume (0.021L+0.0066L=0.0276L) to obtain the concentration of the final salt:

$[salt]=0.01428mol/0.0276L=0.517M$

Now, we need to keep in mind that this is an acidic salt since the base is weak and the acid strong, so the determinant ionization is:

$C_6H_5NH_3^++H_2O\rightleftharpoons C_6H_5NH_2+H_3O^+$

Whose equilibrium expression is:

$Ka=\frac{[C_6H_5NH_2][H_3O^+]}{C_6H_5NH_3^+}$

Now, since the Kb of C6H5NH2 is 4.3 x 10^-10, its Ka is 2.326x10^-5 (Kw/Kb), we can also write:

$2.326x10^{-5}=\frac{x^2}{0.517M}$

Whereas x is:

$x=\sqrt{0.517*2.326x10^{-5}}\\\\x=3.47x10^-3$

Which also equals the concentration of hydrogen ions; therefore, the pH at the equivalence point is:

$pH=-log(3.47x10^{-3})\\\\pH=2.46$

Regards!

6 0

3 years ago

1.Which best explains why ionization energy tends to decrease from the top to the bottom of a group?

tamaranim1 [39]

1.Which best explains why ionization energy tends to decrease from the top to the bottom of a group?

D.Electrons get farther from the nucleus. They experience a weaker attraction to the positive charge of the nucleus.

3.When electrons are removed from the outermost shell of a calcium atom, the atom becomes

D. a cation that has a smaller radius than the atom. Since the atom is losing an electron, it not only becomes positively charged, also the effective nuclear charge diminishes making the remaining electrons aproach the nucleus.

8 0

4 years ago

Read 2 more answers

If a trait varies greatly within a pair of identical twins, it is most likely caused by what?

notsponge [240]

Answer:

1. B. environment

2. A. true

Explanation:

6 0

3 years ago