VIENNA—Austria’s third conservative chancellor in two months, Karl Nehammer, took office on Monday seeking to bring the coalition government out of months of scandal-tainted turmoil and guide the country out of its current coronavirus lockdown. Nehammer, 49, was sworn in by President Alexander Van der Bellen soon after 1 p.m. (12:00 GMT). As interior minister since last year, he was the enforcer of former Chancellor Sebastian Kurz’s hard line on immigration and of four national lockdowns. He is now the first head of government of the post-Kurz era. “We do not know what the virus will surprise us with next,” Van der Bellen said at the swearing-in, ahead of which Nehammer was booed by a small crowd of people protesting against coronavirus restrictions. “We should not create false expectations and should not promise anything that later turns out not to be achievable,” Van der Bellen said in an apparent swipe …