Which examples of science rather than pseudoscience

Which has the lowest freezing point?

kari74 [83]

Answer:

It is D.

Explanation:

5 0

3 years ago

Identifying Isotopes

Otrada [13]

Answer:

The parent isotope in the given elements is Radium 226. 

Explanation:

The two elements given in the question are radioactive elements radon and Helium which are formed after an Alpha decay happens in the radium 226 to form Radon 222.

Radon has many isotopes out of which here radon 222 is formed which is a noble gas that is odourless colourless but Radioactive. Again in this reaction helium is formed which is again a noble gas and very light in weight.

5 0

3 years ago

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What is the density of nitrogen gas if 0.186 g occupies a volume of 110 mL?

Anvisha [2.4K]

Answer:

$d=1.69\times 10^{-3}\ g/mL$

Explanation:

Given that,

Mass, m = 0.186 g

Volume occupies, V = 110 mL

We need to find the density of Nitrogen gas. The mass per unit volume is called density of an object. It is given by the formula as follows :

$d=\dfrac{m}{V}\\\\d=\dfrac{0.186\ g}{110\ mL}\\\\=1.69\times 10^{-3}\ g/mL$

So, the required density is $1.69\times 10^{-3}\ g/mL$ .

4 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

Solid iron sulfide combines with aqueous hydrogen chloride to form hydrogen sulfide gas and aqueous iron chloride.

KIM [24]

Answer:

Fe2S3 + 6HCl → 3H2S + 2FeCl3 is a double-displacement reaction

Explanation:

Step 1: The balanced equation

Fe2S3 + 6HCl → 3H2S + 2FeCl3

Step 2:

Decomposition: This is a reaction in which a compound breaks down into two or more simpler substances. Most decomposition reactions require an input of energy in the form of heat, light, or electricity.

The general form of a decomposition reaction is: AB→A+B

In our case, this is not a decomposition reaction.

Synthesis: This is a type of chemical reaction in which two or more simple substances combine to form a more complex product. The reactants may be elements or compounds, while the product is always a compound.

The general form of a decomposition reaction is: A + B → AB

In our case, this is not a synthesis reaction.

Single-displacement reaction: This is a reaction in which one element replaces a similar element in a compound. The general form of a single-replacement (also called single-displacement) reaction is:

A+BC→AC+B

In our case, this is not a single-displacement reaction.

Double - displacement reaction: This is a reaction in which the positive and negative ions of two ionic compounds exchange places to form two new compounds. The general form of a double-replacement (also called double-displacement) reaction is:

AB+CD→AD+B

In this reaction, A and C are positively-charged cations, while B and D are negatively-charged anions. Double-replacement reactions generally occur between substances in aqueous solution. In order for a reaction to occur, one of the products is usually a solid precipitate, a gas, or a molecular compound such as water.

In our case: There occurs a duble replacement between Fe^3+ and S^2- with H+ and Cl-.

Fe2S3 + 6HCl → 3H2S + 2FeCl3 is a double-displacement reaction

8 0

3 years ago