Determination of molecolar weight by asmotic pe

Which best describes the total mass of substances before and after a combustion reaction? A. The mass is the same because the molecules do not change. B. The mass is the same because atoms are not created or destroyed. C. The mass is less after the reaction because gases are produced. D. The mass is greater after the reaction because the number of atoms increases.

The half-life of the radioactive element unobtanium- 47 is 10 seconds. If 80 grams of unobtanium- 47 are initially present, how many grams are present after 10 seconds? 20 seconds? 30 seconds? 40 seconds? 50 seconds?

The electronic configuration of one element is \(1s^ 2 2s^ 2 2p^ 6 3s^ 2 3p^ 6 3d^ { 10} 4s^ 1\). What is same group which is recently discovered?

At what temperatures is an exothermic reaction spontaneous? A. At higher temperatures when the change in entropy is negative B. At no temperatures C. At all temperatures all the time D. At all temperatures when the change in entropy is positive

Tenga en cuenta la ley de los gases para resolver los siguientes ejercicios ( 1.0 puntos). Un gas se encuentra en un recipiente cilíndrico con diámetro 160 cm y 0.9 m de alto a una presión de 950 mmHg y \( 220^{\circ} \mathrm{F} \). ¿Qué presión se debe ejercer para ocupar un volumen de \( 1,9 \mathrm{~m}^{3} \) a \( 320^{\circ} \mathrm{C} \) ? ( 0.7 puntos). Si en un recipiente con \( 1 \mathrm{~m}^{3} \) de volumen a 1.4 atm y 80 K , se encuentra Oxigeno \( \left(\mathrm{O}_{2}\right) \) ¿Cuántos kilogramos del gas contendrá dicho recipiente?.