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Questions in chemistry

[Answered] Now that we have put a coefficient of 2 in front of $NaNO _3$, what coefficient should go in front of $PbCl _2$ to balance lead $( Pb )$ ? $Pb(NO_3)_2+NaCl \rightarrow ? PbCl_2+2 NaNO_3$ Express your answer numerically as an integer.

[Answered] Which chemical symbol represents a metalloid? A. B B. Al C. Ga D. Zn E. Ar

[Answered] Which is a substance that is made up of only one type of atom? A. compound B. element C. solution D. mixture

[Answered] What would happen to the rate of a reaction with rate law rate $=k[ NO ]^2\[ H _2\]$ if the concentration of NO were halved? A. The rate would be doubled. B. The rate would be four times larger. C. The rate would be one-fourth. D. The rate would also be halved.

[Answered] Which property describes a mixture? A. It cannot be separated by physical methods. B. It has a single chemical composition. C. It cannot have more than one state of matter. D. It cannot be described by a chemical symbol or formula.

[Answered] Which represents the balanced nuclear equation for the beta plus decay of C-11? ${ }_6^{11} C \longrightarrow{ }_5^{11} B+{ }_{+1}^0 e$ ${ }_6^{11} C \longrightarrow{ }_7^{11} N+{ }_{+1}^0 e$ ${ }_6^{11} C \longrightarrow{ }_7^{11} N+{ }_{-1}^0 e$ ${ }_6^{11} C \longrightarrow{ }_5^{11} B+{ }_{-1}^0 e

[Answered] Aqueous solutions of acids conduct electricity because of free moving: (a) Molecules (b) Ions (c) Electrons (d) All of these

[Answered] Which substance in this redox reaction is the oxidizing agent? $Cu+2 AgNO_3 \rightarrow 2 Ag+Cu\left(NO_3\right)_2$ A. N B. $AgNO _3$ C. Cu D. $NO _3{ }^{-}$ E. $Cu \left( NO _3\right)_2$

[Answered] A student is studying chemical changes and mixes two liquid compounds. Which statement best describes what the student should observe if a chemical reaction is occurring? A. The two substances dissolve. B. A solid substance appears. C. The mass of the substances increases. D. The temperature of the substances stays the same.

[Answered] The half-life of a particular radioactive substance is 1 year. If you started with 50 grams of this substance, how much of it would remain after 3 years? Remaining Amount $=50$ ( $1-$ [?]) Remaining Amount $= I (1-r)^{ t }$