What doubly positive ion has the following ground-state electron configuration? $1 s^2 2 s^2 2 p^6 3 s^2 3 p^6 3 d^{15}$

At $50 ^ { \circ } \mathrm { C }$ the ion-product constant for $H_2O$ has the value $K _ { w } = 5.48 \times 10 ^ { - 14 }$ Based on the change in $K_w$ with temperature, predict whether $\Delta H$ is positive, negative, or zero for the autoionization reaction of water: $2 \mathrm { H } _ { 2 } \mathrm { O } ( l ) \rightleftharpoons \mathrm { H } _ { 3 } \mathrm { O } ^ { + } ( a q ) + \mathrm { OH } ^ { - } ( a q )$

Evaluate each express ion if x=6.

$$2 x \div 6$$

(a) An oxygen-16 ion with a mass of $2.66 \times 10^{-26} \mathrm{kg}$ travels at $5.00 \times 10^{6} \mathrm{m} / \mathrm{s}$ perpendicular to a 1.20-T magnetic field, which makes it move in a circular arc with a 0.231-m radius. What positive charge is on the ion? (b) What is the ratio of this charge to the charge of an electron? (c) Discuss why the ratio found in (b) should be an integer.

In an aqueous solution, which substance yields hydrogen ions as the only positive ion? (1) $\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}$, (2) $\mathrm{CH}_{3} \mathrm{COOH}$, (3) KH, (4) KOH.

Potassium ions $\left(\mathrm{K}^{+}\right)$have a positive charge. What happens to a potassium atom's electrons when it becomes an ion?

Give the formula of a negative ion that would have the same number of electrons as each of the following positive ions. a. $\mathrm{K}^{+}$ b. $\mathrm{Mg}^{2+}$ c. $\mathrm{Sr}^{2+}$ d. $\mathrm{Cs}^{+}$

Write the complete chemical formula (symbol and charge) for the positive ion present in each of the following ionic compounds.

a. KCl

b. CaS

c. $\text{MgF}_2$

d. $\text{Al}_2\text{S}_3$

Use inversion to turn the following statement into question.

Il fait mauvais aujourd’hui.

Give the formula of a negative ion that would have the same number of electrons as each of the following positive ions. $\mathrm{Rb}^{+}$

$(a)$ An oxygen-$16$ ion with a mass of $2.66 \times 10^{-26} \mathrm{~kg}$ travels at $5.0 \times 10^6 \mathrm{~m} / \mathrm{s}$ perpendicular to a $1.20 \mathrm{~T}$ magnetic field, which makes it move in a circular arc with a $0.231 \mathrm{~m}$ radius. What positive charge is on the ion? $(b)$ What is the ratio of this charge to the charge of an electron? $(c)$ Discuss why the ratio found in $(b)$ should be an integer.

Pressure is defined as the ______ per unit area.

Which of the following compounds would you expect to be ionic and which molecular (covalent)? (a) $\mathrm{LiBr}$ (b) $\mathrm{SiCl}_4$ (c) $\mathrm{BF}_3$ (d) $\mathrm{CaO}$

A toy manufacturer buys ball bearings from three different suppliers-50% of her total order comes from supplier 1, 30% from supplier 2, and the rest from supplier 3. Past experience has shown that the quality-control standards of the three suppliers are not all the same. Two percent of the ball bearings produced by supplier 1 are defective, while suppliers 2 and 3 produce defective bearings 3% and 4% of the time, respectively. What proportion of the ball bearings in the toy manufacturer’s inventory are defective?