【单选题】
如果<img class="kfformula" src="20190808/1565251013539366.png" data-latex="ab"/>,那么下列不等式正确的是( )
①
<img class="kfformula" src="20190808/1565251013586057.png" data-latex="\frac {1} {2}a\frac {1} {2}b"/>
②
<img class="kfformula" src="20190808/1565251013931183.png" data-latex="-3a-3b"/>
③
<img class="kfformula" src="20190808/1565251013130324.png" data-latex="5a5b"/>
④
<img class="kfformula" src="20190808/1565251013738499.png" data-latex="a-2b-2"/>
【单选题】
<img class="kfformula" src="20190808/1565256388580621.png" data-latex="{25}^{\frac {3} {2}}="/>( )
【单选题】
今有360本图书借给学生阅读,每人9本,则余下的书数<img class="kfformula" src="20190924/1569292387333325.png" data-latex="y"/>(本)和学生数<img class="kfformula" src="20190924/1569292387869597.png" data-latex="x"/>(个)之间的函数关系式为( )
①
<img class="kfformula" src="20190924/1569292387325349.png" data-latex="y=40/x"/>
②
<img class="kfformula" src="20190924/1569292387912197.png" data-latex="y=9*x"/>
③
<img class="kfformula" src="20190924/1569292387266041.png" data-latex="y=360-9x"/>
④
<img class="kfformula" src="20190924/1569292387456376.png" data-latex="y=360+9x"/>
【单选题】
飘尘是物质燃烧时产生的粒状漂浮物,颗粒很小,不易沉降。它与空气中的<img class="kfformula" src="20200629/1593438466954477.png" data-latex="{SO}_{2}和{O}_{2}" width="64" height="35"/>接触时,<img class="kfformula" src="20200629/1593438466347645.png" data-latex="{SO}_{2}" width="38" height="32"/>会部分转化为<img class="kfformula" src="20200629/1593438466997886.png" data-latex="{SO}_{3}" width="42" height="37"/>,使空气的酸度增加,环境污染更为严重。其中飘尘所起的作用可能是()。
【单选题】
用pH均为2的盐酸和醋酸溶液,分别中和等体积、等物质的量浓度的氢氧化钠溶液,当氢氧化钠恰好完全中和时,消耗盐酸和醋酸溶液的体积分别为<img class="kfformula" src="20200629/1593410807763639.png" data-latex="{V}_{1}和{V}_{2}" width="62" height="26"/>,则<img class="kfformula" src="20200629/1593410807313382.png" data-latex="{V}_{1}和{V}_{2}" width="61" height="22"/>的关系正确的是()。
①
<img class="kfformula" src="20200629/1593410807121645.png" data-latex="{V}_{1}{V}_{2}" width="65" height="36"/>
②
<img class="kfformula" src="20200629/1593410807286465.png" data-latex="{V}_{1}={V}_{2}" width="78" height="34"/>
③
<img class="kfformula" src="20200629/1593410807420867.png" data-latex="{V}_{1}\leq {V}_{2}" width="69" height="37"/>
④
<img class="kfformula" src="20200629/1593410807799986.png" data-latex="{V}_{1}{V}_{2}" width="73" height="29"/>
【单选题】
有0.1mol/L<img class="kfformula" src="20200707/1594087695131974.png" data-latex="{Na}_{2}{SO}_{4}" width="77" height="30"/>溶液300mL,0.1mol/L<img class="kfformula" src="20200707/1594087695248793.png" data-latex="{MgSO}_{4}" width="70" height="30"/>溶液200mL和0.1mol/L<img class="kfformula" src="20200707/1594087695350060.png" data-latex="{Al}_{2}{({SO}_{4})}_{3}" width="83" height="31"/>溶液100mL,这三种溶液中硫酸根离子物质的量浓度之比是( )。
【单选题】
<img class="kfformula" src="20190808/1565256297772060.png" data-latex="\sqrt {\left ( {lg5-1} \right )^{2}}"/>的值等于( )
①
<img class="kfformula" src="20190808/1565256297983776.png" data-latex="lg\frac {1} {5}"/>
②
<img class="kfformula" src="20190808/1565256297148379.png" data-latex="lg5-1"/>
③
<img class="kfformula" src="20190808/1565256297764160.png" data-latex="lg5"/>
④
<img class="kfformula" src="20190808/1565256297303551.png" data-latex="lg2"/>
【单选题】
函数<img class="kfformula" src="20190808/1565253438624934.png" data-latex="y=2-{x}^{2}"/>的单调递减区间是( )
①
<img class="kfformula" src="20190808/1565253438467999.png" data-latex="\left ( {-\infty ,0} \right )"/>
②
<img class="kfformula" src="20190808/1565253438403956.png" data-latex="\left ( {-\infty ,-1} \right )"/>
③
<img class="kfformula" src="20190808/1565253438303182.png" data-latex="\left ( {-1,+\infty } \right )"/>
④
<img class="kfformula" src="20190808/1565253438117832.png" data-latex="\left ( {0,+\infty } \right )"/>
【单选题】
某元素x的气态氢化物化学式为<img class="kfformula" src="20200706/1594027764184798.png" data-latex="{H}_{2}X" width="59" height="35"/>,下面的叙述不正确的是( )。
①
该元素最高价氧化物的化学式为<img class="kfformula" src="20200706/1594027764536194.png" data-latex="{XO}_{3}" width="74" height="39"/>
③
该元素最高价氧化物对应水化物的化学式为<img class="kfformula" src="20200706/1594027764169500.png" data-latex="{H}_{2}{XO}_{3}" width="72" height="43"/>
【单选题】
下列函数中,在区间<img class="kfformula" src="20190808/1565255863544549.png" data-latex="\left ( {-\infty ,+\infty } \right )"/>内为增函数的是( )
①
<img class="kfformula" src="20190808/1565255863279980.png" data-latex="y=2-x"/>
②
<img class="kfformula" src="20190808/1565255863845028.png" data-latex="y={3}^{x}"/>
③
<img class="kfformula" src="20190808/1565255863797150.png" data-latex="y={x}^{-2}"/>
④
<img class="kfformula" src="20190808/1565255863844363.png" data-latex="y={log}_{0.3}x"/>