One thing incorrect is that when dealing with a compound, such as H2SO4, that has 7 atoms in the chemical formula, the polyatomic ion SO4 doesn’t dissociate into one Sulfur and four Oxygens. SO4 stays and a PAI.
Answer:
Todas son correctas
Explanation:
I) Los compuestos del carbono son solubles en disolventes no polares como el hexano, benceno, éter, etc. <em>VERDADERO. </em>La mayoría de los compuestos de carbono son apolares, y basados en la regla: Similar disuelve similar, podemos presumir que la mayoría de compuestos de carbono se disuelven en solventes no polares.
II) Los compuestos del carbono generalmente presentan puntos de fusión y de ebullición bajos. <em>VERDADERO. </em>Al ser sustancias apolares, sus fuerzas electrostáticas son bajas. De la misma manera, como su masa atómica es pequeña, las fuerzas de Van der Waals son despreciables haciendo que sus puntos de fusión y ebullición sean bajos respecto a sustancias de estrucutra similar.
III) La gran mayoría de los compuestos del carbono son combustibles, sean estos, gaseosos, líquidos o sólidos. <em>VERDADERO. </em>Los gases (Como el gas natural) son combustibles usados para cocina. Los líquidos (Como la gasolina) son combustibles y bastante inflamables. Los sólidos (Como la madera) se usan como combustibles para hacer asados o son el combustible en incendios forestales.
IV) El enlace covalente es característico de los compuestos del carbono. <em>VERDADERO. </em>La polaridad del carbono es neutral haciendo que la mayoría de los enlaces que forma sean covalentes.
<h3>Todas son correctas
</h3>
<span>pre-1982 definition STP: 120 g/mol
post-1982 definition STP: 122 g/mol
The answer to this question depends upon which definition of STP you're using. The definition changed in 1982 from 273.15 K at 1 atmosphere to 273.15 K at 10000 pascals. As a result the molar volume of a gas at STP changed from 22.4 L/mol to 22.7 L/mol. So let's calculate the answer using both definitions and see if your text book is 35 years obsolete.
First, determine the number of moles of gas you have. Do this by dividing the volume you have by the molar volume. So
pre-1982: 0.04665 / 22.4 = 0.002082589 mol
post-1982: 0.04665 / 22.7 = 0.002055066 mol
Now divide the mass you have by the number of moles.
pre-1982: 0.250 g / 0.002082589 mol = 120.0428725 g/mol
post-1982: 0.250 g / 0.002055066 mol = 121.6505895 g/mol
Finally, round to 3 significant figures:
pre-1982: 120 g/mol
post-1982: 122 g/mol
These figures are insanely large for nitrogen gas. So let's see if our input data is reasonable. Looking up the density of nitrogen gas at STP, I get a value of 1.251 grams per liter. The value of 0.250 grams in the problem would then imply a volume of about one fifth of a liter, or about 200 mL. That is over 4 times the volume given of 46.65 mL. So the verbiage in the question mentioning "nitrogen gas" is inaccurate at best.
I see several possibilities.
1. The word "nitrogen" was pulled out of thin air and should be replaced with "an unknown"
2. The measurements given are incorrect and should be corrected.
In any case, if #1 above is the correct reason, then you need to pick the answer based upon which definition of STP your textbook is using.</span>
Answer: Iodine
Explanation:
Atomic radius decreases across the period due to the increase in the size of the nuclear charge without a corresponding increase in the number of shells. The atoms become smaller from left to right across the period table. This is the reason why atomic radius decreases across the period.
