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【单选题】
醋酸溶液中,加入适量固体 NaAc 后,结果会使( )
A.
溶液 pH 值增大
B.
溶液 pH 值减小
C.
醋酸解离常数增大
D.
醋酸解离常数减小
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【单选题】the primary reason for the malleability of metal is ( ).
A.
the nondirectional nature of metallic bonding
B.
the slide ability of planes of atoms in a metal under stress
C.
the bonds between atons breaking of covalently bonded crystals
D.
a gas of nearly free electrons formed by the outer electrons of the metal atoms
查看完整题目与答案
【单选题】What is the main idea of the following paragraph? Iron is the most common metal in today's society. It is used in the construction industry, vehicle manufacturing, machinery, cookware, weapons and too...
A.
i Iron is very plentiful
B.
ii Iron is a useful metal
C.
iii Steel beams are made of iron
查看完整题目与答案
【单选题】The primary reason for the malleability of metal is?
A.
the nondirectional nature of metallic bonding
B.
the slide ability of planes of atoms in a metal under stress
C.
the bonds between atoms breaking of covalently bonded crystals
D.
a gas of nearly free electrons formed by the outer electrons of the metal atoms
查看完整题目与答案
【单选题】有关温度对酶活性的影响,正确的是?
A.
低温可以使酶失活
B.
催化的反应速度随温度升高而升高
C.
最适温度是酶的特征性常数
D.
最适温度随反应的时间而有所改变
E.
以上全不对
查看完整题目与答案
【单选题】世界上最早建设高速铁路的国家是( )
A.
法国
B.
中国
C.
日本
D.
德国
查看完整题目与答案
【判断题】Because the total concentration of a polluting element in an environmental sample provides no information concerning the fate of the element in terms of its interaction with sediment, its ability to c...
A.
正确
B.
错误
查看完整题目与答案
【单选题】Toughness is ______ ability of a metal to resist, or absorb, sudden shocks of loads without breaking.
A.
a
B.
an
C.
the
D.
which
查看完整题目与答案
【单选题】下列有关温度对酶活性影响的说法,哪一个是正确的? 答( )
A.
①温度从摄氏 80 ° 至 90 ° 升高 10 ° ，通常使反应速度增加 1 倍；
B.
②温度升高使酶促反应的活化能降低；
C.
③温度从摄氏 25 ° 升至 35 ° 使具有活化能的反应物分子数增加；
D.
④温度升高不影响酶促反应的平衡常数
查看完整题目与答案
【单选题】有关温度对酶活性影响不正确的是
A.
最适温度不是酶的特征性常数
B.
酶是蛋白质，即使反应的时间很短也不能提高反应温度
C.
酶制剂在低温下保存
D.
酶的最适温度与反应时间有关
查看完整题目与答案
【判断题】Because the total concentration of a polluting element in an environmental sample provides no information concerning the fate of the element in terms of its interaction with sediment, its ability to c...
A.
正确
B.
错误
查看完整题目与答案
相关题目：
【单选题】the primary reason for the malleability of metal is ( ).
A.
the nondirectional nature of metallic bonding
B.
the slide ability of planes of atoms in a metal under stress
C.
the bonds between atons breaking of covalently bonded crystals
D.
a gas of nearly free electrons formed by the outer electrons of the metal atoms
查看完整题目与答案
【单选题】What is the main idea of the following paragraph? Iron is the most common metal in today's society. It is used in the construction industry, vehicle manufacturing, machinery, cookware, weapons and too...
A.
i Iron is very plentiful
B.
ii Iron is a useful metal
C.
iii Steel beams are made of iron
查看完整题目与答案
【单选题】The primary reason for the malleability of metal is?
A.
the nondirectional nature of metallic bonding
B.
the slide ability of planes of atoms in a metal under stress
C.
the bonds between atoms breaking of covalently bonded crystals
D.
a gas of nearly free electrons formed by the outer electrons of the metal atoms
查看完整题目与答案
【单选题】有关温度对酶活性的影响,正确的是?
A.
低温可以使酶失活
B.
催化的反应速度随温度升高而升高
C.
最适温度是酶的特征性常数
D.
最适温度随反应的时间而有所改变
E.
以上全不对
查看完整题目与答案
【单选题】世界上最早建设高速铁路的国家是( )
A.
法国
B.
中国
C.
日本
D.
德国
查看完整题目与答案
【判断题】Because the total concentration of a polluting element in an environmental sample provides no information concerning the fate of the element in terms of its interaction with sediment, its ability to c...
A.
正确
B.
错误
查看完整题目与答案
【单选题】Toughness is ______ ability of a metal to resist, or absorb, sudden shocks of loads without breaking.
A.
a
B.
an
C.
the
D.
which
查看完整题目与答案
【单选题】下列有关温度对酶活性影响的说法,哪一个是正确的? 答( )
A.
①温度从摄氏 80 ° 至 90 ° 升高 10 ° ，通常使反应速度增加 1 倍；
B.
②温度升高使酶促反应的活化能降低；
C.
③温度从摄氏 25 ° 升至 35 ° 使具有活化能的反应物分子数增加；
D.
④温度升高不影响酶促反应的平衡常数
查看完整题目与答案
【单选题】有关温度对酶活性影响不正确的是
A.
最适温度不是酶的特征性常数
B.
酶是蛋白质，即使反应的时间很短也不能提高反应温度
C.
酶制剂在低温下保存
D.
酶的最适温度与反应时间有关
查看完整题目与答案
【判断题】Because the total concentration of a polluting element in an environmental sample provides no information concerning the fate of the element in terms of its interaction with sediment, its ability to c...
A.
正确
B.
错误
查看完整题目与答案