All categories

3 years ago

Which substance can not be broken down by a chemical change? A)methane B)propanal C) tungsten D)water

Chemistry

2 answers:

valentinak56 [21]3 years ago

6 0

Answer:

The substance that cannot be broken down by a chemical change is tungsten (option C)

Explanation:

Chemical compounds are pure substances constituted by two or more different elements. They have fixed composition and have their unique chemical properties, different from their individual components (elements) and from other compounds.

Thus chemical compounds can be broken down by a chemical change into their individual atoms or other simpler compounds.

The substances indicated by the choices A) methane, B) propanal, and D) water, are chemical compounds with chemical formulae CH₄, C₃H₆O, and H₂O, respectively, so they can be broken down into their consitutents by a chemical change.

On the other hand, tungsten is one of the 118 known elements. Its atomic number is 74, and its chemical symbol is W.

Then, being tungsten an element, which means that all the atoms present in a pure sample have the same number of protons and electrons, it cannot be broken down by a chemical change. The only way to split an atom of tungsten is by a nuclear reaction.

luda_lava [24]3 years ago

3 0

Answer:

$\huge \boxed{\mathrm{C) \ Tungsten}}$

Explanation:

Tungsten cannot be broken by any physical or chemical methods, because it is an element. It has properties of an element not a compound nor mixture.

Tungsten is an element in the periodic table with an atomic number of 74, symbol W, and atomic mass of 183.84 u.

Tungsten is also a rare metal and is the strongest known metal on Earth. Tungsten can be used to make bullets and missiles.

You might be interested in

What would happen if you play a note in a cold day on a flute?

Maurinko [17]

I don't know if this is the answer you are looking for but it would be flat unless the player pushed the tuning slide in.

7 0

3 years ago

3. If you start with 8x1025 molecules of Cl, and 25 grams of KI, how many grams of KCl would

miskamm [114]

Answer:

Percent yield = 89.1%

Explanation:

Based on the equation:

Cl₂ + 2KI → 2KCl + I₂

1 mole of Cl₂ reacts with 2 moles of KI to produce to moles of KCl

To solve this quesiton we must find the moles of each reactant in order to find the limiting reactant. With the limiting reactant we can find the moles of KCl and the mass:

Moles Cl₂:

8x10²⁵ molecules * (1mol / 6.022x10²³ molecules) = 133 moles

Moles KI -Molar mass: 166.0028g/mol-

25g * (1mol / 166.0028g) = 0.15 moles

Here, clarely, the KI is the limiting reactant

As 2 moles of KI produce 2 moles of KCl, the moles of KCl produced are 0.15 moles. The theoretical mass is:

0.15 moles * (74.5513g / mol) =

11.2g KCl

Percent yield is: Actual yield (10.0g) / Theoretical yield (11.2g) * 100

<h3>Percent yield = 89.1%</h3>

3 0

3 years ago

Two hydrogen atoms collide in a head on collision and end up with zero kinetic energy. Each then emits a photon of 121.6 nm (n=2

Zinaida [17]

Explanation:

Expression for the kinetic energy is as follows.

K.E = $\frac{1}{2}mv^{2}$

Now, total kinetic energy will be as follows.

K.E = $2 \times \frac{1}{2}mv^{2}$ = $m \times v^{2}$

Since, this energy converts into electromagnetic radiation of wavelength 121.6 nm.

Relation between energy and photon is as follows.

Energy of photon = $\frac{hc}{\lambda}$

= $\frac{6.626 \times 10^{-34} \times 3 \times 10^{8}}{121.6 \times 10^{-9}}$

= $1.63 \times 10^{-18} J$

$m \times v^{2} = 1.63 \times 10^{-18}$

v = $\sqrt{\frac{1.63 \times 10^{-18}}{1.67 \times 10^{-27}}$

= $3.12 \times 10^{4}$ m/s

Thus, we can conclude that atoms were moving at a speed of $3.12 \times 10^{4}$ m/s before the collision.

8 0

3 years ago

How long does it take me to travel 500 m E at a velocity of 50 m/s E?

konstantin123 [22]

Answer:15 s E

Explanation:

7 0

3 years ago

Cyclic compound A has molecular formula C5H10 and undergoes monochlorination to yield exactly three different constitutional iso

RideAnS [48]

Answer:

A: 1,2-dimethylcyclopropane

Explanation:

The possible cyclic structure with formula C₅H₁₀ are shown in the image.

A is a cyclic compound. On monochlorination, A yields 3 products.

To have 3 products on monochlorination, there should be three different carbon atoms.

Considering structure 1, all carbons have same nature, thus only one product will be formed and thus not a structure of A.

Considering structure 2, there are two different carbon atoms, thus two different structure are formed and thus not a structure of A.

Considering structures 3 and 4 , there are four different carbon atoms, thus four products will be formed and either of them are not a structure of A.

Considering structure 5, there are three different carbon atoms, thus three different structure are formed and thus the A is structure 5.

4 0

3 years ago