The boldest attack was near the northern city of Mosul, where militants set up a fake security checkpoint, captured five soldiers and shot them dead, a police officer said.
The soldiers were dressed in civilian clothes and returning to base in a taxi, he added.
Inside Mosul, another group of gunmen in a speeding car shot and killed a grocer, he said, adding that the motive was not immediately clear.
The grocer was a member of the Shabak ethnic group, which has its own distinct language and religious beliefs.
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Another police officer said a car bomb exploded as a judge drove past in the northern town of Balad, killing three nurses and a man who had been walking nearby.
Thirteen other people were wounded, including the judge, his brother and the driver, he added.
In Baghdad's southeastern and largely Shiite neighbourhood of al-Ameen, a car bomb at a market killed three civilians and wounded 13 others, a police officer said.
Another car bomb killed four other civilians and wounded 12 in the town of Madain, about 25 kilometres southeast of Baghdad, another police officer said.
Baqouba is about 60 kilometres northeast of Baghdad.
Five medical officials confirmed the casualty figures. All spoke on condition of anonymity as they were not authorised to release the information.
Attacks have been on the rise in Iraq since a deadly security crackdown in April on a Sunni protest camp.
More than 3,000 people have been killed in violence during the past few months, raising fears the country could see a new round of widespread sectarian bloodshed similar to that which brought it to the edge of civil war in 2006 and 2007.