【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】
关于维生素<img class="kfformula" src="20200424/1587719873847609.png" data-latex="{K}_{1}" width="39" height="26"/>的描述,下列说法错误的是( )。
①
注射后1~2h起效,3~6h止血效应明显,12~24h后<img class="kfformula" src="20200424/1587719873825079.png" data-latex="PT" width="44" height="27"/>恢复正常
②
维生素<img class="kfformula" src="20200424/1587719873963754.png" data-latex="{K}_{1}" width="39" height="26"/>主要在胃内吸收
③
维生素<img class="kfformula" src="20200424/1587719873577601.png" data-latex="{K}_{1}" width="39" height="27"/>为促凝血因子合成药
④
维生素<img class="kfformula" src="20200424/1587719873539508.png" data-latex="{K}_{1}" width="39" height="27"/>缺乏可引起出血倾向和凝血酶时间(<img class="kfformula" src="20200424/1587720020548019.png" data-latex="PT" width="42" height="27"/>)延长
【单选题】
P单质在反应<img class="kfformula" src="20200629/1593418632407394.png" data-latex="4P+3KOH+{3H}_{2}O==={3KH}_{2}{PO}_{2}+{PH}_{3}" width="297" height="34"/>中的变化是( )。
【单选题】
设<img class="kfformula" src="20200624/1592994530966484.png" data-latex="{N}_{A}" width="49" height="27"/>为阿伏加德罗常数的值,现有0.3mol/L<img class="kfformula" src="20200624/1592994530304513.png" data-latex="{K}_{2}{SO}_{4}" width="61" height="30"/>溶液,2L溶液中钾离子的浓度为( )mol/L。
【单选题】
设<img class="kfformula" src="20200706/1594009368539359.png" data-latex="{N}_{A}" width="57" height="28"/>为阿伏加德罗常数的值,现有0.3mol/L<img class="kfformula" src="20200624/1592993842192203.png" data-latex="{K}_{2}{SO}_{4}" width="51" height="31"/> 溶液,1L溶液中钾离子有( )<img class="kfformula" src="20200624/1592993842591471.png" data-latex="{N}_{A}" width="57" height="34"/>个。
【单选题】
不等式<img class="kfformula" src="20190808/1565250723184457.png" data-latex="{x}^{2}-2x-80"/>的解集是( )
①
<img class="kfformula" src="20190808/1565250723229267.png" data-latex="\left ( {4,+\infty } \right )"/>
②
<img class="kfformula" src="20190808/1565250723616994.png" data-latex="\left ( {-\infty ,-2} \right )\cup \left ( {4,+\infty } \right )"/>
③
<img class="kfformula" src="20190808/1565250723532354.png" data-latex="\left ( {-\infty ,-2} \right )"/>
④
<img class="kfformula" src="20190808/1565250723744347.png" data-latex="\left ( {-2,4} \right )"/>
【单选题】
<img class="kfformula" src="20200707/1594090277136567.png" data-latex="将足量Zn与5L的0.1mol/L\, \, {H}_{2}{SO}_{4}溶液反应" width="370" height="32"/>,<img class="kfformula" src="20200706/1594022732803813.png" data-latex="可以生成(\, \, \, )mol的氢气。\, \, " width="201" height="31"/>
【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】
两条平行直线<img class="kfformula" src="20190809/1565322829875215.png" data-latex="3x+4y-7=0"/>和<img class="kfformula" src="20190809/1565322829154016.png" data-latex="3x+4y+8=0"/>之间的距离是( )
①
<img class="kfformula" src="20190809/1565322829886592.png" data-latex="3"/>
②
<img class="kfformula" src="20190809/1565322829721740.png" data-latex="3\sqrt {2}"/>
③
<img class="kfformula" src="20190809/1565322829406438.png" data-latex="15"/>
④
<img class="kfformula" src="20190809/1565322829833725.png" data-latex="\frac {1} {5}" width="87" height="63"/>
【单选题】
将0.lmol·<img class="kfformula" src="20200629/1593409309479184.png" data-latex="{L}^{-1}" width="46" height="31"/>醋酸溶液加水稀释,下列说法正确的是()。
①
溶液中c(<img class="kfformula" src="20200629/1593409309358634.png" data-latex="{H}^{+}" width="36" height="32"/>)和c(<img class="kfformula" src="20200629/1593409309469275.png" data-latex="{OH}^{-}" width="55" height="27"/>)都减小
②
溶液中c(<img class="kfformula" src="20200629/1593409309586142.png" data-latex="{H}^{+}" width="45" height="26"/>)增大