A flask is charged with 0.124 mol of A and allowed to react to form B according to the reaction A(g) →B(g). The following data are obtained for [A] as the reaction proceeds:

Time (s) 0.00 - 10.0 - 20.0 - 30.0 - 40.0
Moles A 0.124 - 0.110 - 0.088 - 0.073 - 0.054

The average rate of disappearance of A between 10 s and 20 s is mol/s.

A) 2.2 × 10⁻³
B) 1.1 × 10⁻³
C) 4.4 × 10⁻³
D) 454
E) 9.90 × 10⁻³

For a family dinner, jose’s mom baked a loaf of bread. during the meal, his grandmother commented, “this bread is so dense! ” what do you think his grandmother meant by the word dense? you have some ideas regarding density already, but this experiment will enrich your understanding of the relationship between mass, volume and the density of objects. when making measurements in this experiment we will be using si units, the international system of units. the purpose of using si units is to have the ability to communicate and compare data results with other experiments without having to make conversions. measurement symbol si unit length m meter mass kg kilogram volume l liters density kg/l kilograms per liter any calculations that are performed during this experiment will ultimately be reported in scientific notation. recall that scientific notation is extremely important when we have data that is extremely small or large. scientists rely on a standard form of communication to quickly make hypotheses and judgements based on data. what is the density of block a? a0kg/l what is the density of block b? a1kg/l what is the density of block c? a2kg/l what is the density of block d? a3kg/l what is the density of block e? a4kg/l which block is the densest? a5

With the largest atoms and the smallest number of valence electrons and with the smallest atoms and the greatest number of valence electrons are the most reactive. a. nonmetals; metals b. nonmetals; transition elements c. transition elements; metals d. metals; nonmetals

The comparison of the number of atoms in a copper coin the size of a penny with the number of people on earth is made to illustrate which of the following? a. that atoms are indivisible b. that atoms are very small c. that atoms are very large d. that in a copper penny, there is one atom for every person on earth